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3e45d5d9a5
rhai/src/parser.rs
Stephen Chung 3e45d5d9a5 Refine docs and API.
2020-07-06 13:01:57 +08:00

2791 lines
94 KiB
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//! Main module defining the lexer and parser.
use crate::any::{Dynamic, Union};
use crate::calc_fn_hash;
use crate::engine::{make_getter, make_setter, Engine, KEYWORD_THIS};
use crate::error::{LexError, ParseError, ParseErrorType};
use crate::module::{Module, ModuleRef};
use crate::optimize::{optimize_into_ast, OptimizationLevel};
use crate::scope::{EntryType as ScopeEntryType, Scope};
use crate::token::{Position, Token, TokenStream};
use crate::utils::{StaticVec, StraightHasherBuilder};
use crate::stdlib::{
borrow::Cow,
boxed::Box,
char,
collections::HashMap,
fmt, format,
iter::empty,
mem,
num::NonZeroUsize,
ops::Add,
string::{String, ToString},
vec,
vec::Vec,
};
/// The system integer type.
///
/// If the `only_i32` feature is enabled, this will be `i32` instead.
#[cfg(not(feature = "only_i32"))]
pub type INT = i64;
/// The system integer type.
///
/// If the `only_i32` feature is not enabled, this will be `i64` instead.
#[cfg(feature = "only_i32")]
pub type INT = i32;
/// The system floating-point type.
///
/// Not available under the `no_float` feature.
#[cfg(not(feature = "no_float"))]
pub type FLOAT = f64;
type PERR = ParseErrorType;
pub use crate::utils::ImmutableString;
/// Compiled AST (abstract syntax tree) of a Rhai script.
///
/// Currently, `AST` is neither `Send` nor `Sync`. Turn on the `sync` feature to make it `Send + Sync`.
#[derive(Debug, Clone, Default)]
pub struct AST(
/// Global statements.
Vec<Stmt>,
/// Script-defined functions.
Module,
);
impl AST {
/// Create a new `AST`.
pub fn new(statements: Vec<Stmt>, lib: Module) -> Self {
Self(statements, lib)
}
/// Get the statements.
#[cfg(not(feature = "internals"))]
pub(crate) fn statements(&self) -> &[Stmt] {
&self.0
}
/// Get the statements.
#[cfg(feature = "internals")]
#[deprecated(note = "this method is volatile and may change")]
pub fn statements(&self) -> &[Stmt] {
&self.0
}
/// Get a mutable reference to the statements.
pub(crate) fn statements_mut(&mut self) -> &mut Vec<Stmt> {
&mut self.0
}
/// Get the internal `Module` containing all script-defined functions.
#[cfg(not(feature = "internals"))]
pub(crate) fn lib(&self) -> &Module {
&self.1
}
/// Get the internal `Module` containing all script-defined functions.
#[cfg(feature = "internals")]
#[deprecated(note = "this method is volatile and may change")]
pub fn lib(&self) -> &Module {
&self.1
}
/// Clone the `AST`'s functions into a new `AST`.
/// No statements are cloned.
///
/// This operation is cheap because functions are shared.
pub fn clone_functions_only(&self) -> Self {
self.clone_functions_only_filtered(|_, _, _| true)
}
/// Clone the `AST`'s functions into a new `AST` based on a filter predicate.
/// No statements are cloned.
///
/// This operation is cheap because functions are shared.
pub fn clone_functions_only_filtered(
&self,
filter: impl Fn(FnAccess, &str, usize) -> bool,
) -> Self {
let mut functions: Module = Default::default();
functions.merge_filtered(&self.1, filter);
Self(Default::default(), functions)
}
/// Clone the `AST`'s script statements into a new `AST`.
/// No functions are cloned.
pub fn clone_statements_only(&self) -> Self {
Self(self.0.clone(), Default::default())
}
/// Merge two `AST` into one. Both `AST`'s are untouched and a new, merged, version
/// is returned.
///
/// The second `AST` is simply appended to the end of the first _without any processing_.
/// Thus, the return value of the first `AST` (if using expression-statement syntax) is buried.
/// Of course, if the first `AST` uses a `return` statement at the end, then
/// the second `AST` will essentially be dead code.
///
/// All script-defined functions in the second `AST` overwrite similarly-named functions
/// in the first `AST` with the same number of parameters.
///
/// # Example
///
/// ```
/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
/// # #[cfg(not(feature = "no_function"))]
/// # {
/// use rhai::Engine;
///
/// let engine = Engine::new();
///
/// let ast1 = engine.compile(r#"
/// fn foo(x) { 42 + x }
/// foo(1)
/// "#)?;
///
/// let ast2 = engine.compile(r#"
/// fn foo(n) { "hello" + n }
/// foo("!")
/// "#)?;
///
/// let ast = ast1.merge(&ast2); // Merge 'ast2' into 'ast1'
///
/// // Notice that using the '+' operator also works:
/// // let ast = &ast1 + &ast2;
///
/// // 'ast' is essentially:
/// //
/// // fn foo(n) { "hello" + n } // <- definition of first 'foo' is overwritten
/// // foo(1) // <- notice this will be "hello1" instead of 43,
/// // // but it is no longer the return value
/// // foo("!") // returns "hello!"
///
/// // Evaluate it
/// assert_eq!(engine.eval_ast::<String>(&ast)?, "hello!");
/// # }
/// # Ok(())
/// # }
/// ```
pub fn merge(&self, other: &Self) -> Self {
self.merge_filtered(other, |_, _, _| true)
}
/// Merge two `AST` into one. Both `AST`'s are untouched and a new, merged, version
/// is returned.
///
/// The second `AST` is simply appended to the end of the first _without any processing_.
/// Thus, the return value of the first `AST` (if using expression-statement syntax) is buried.
/// Of course, if the first `AST` uses a `return` statement at the end, then
/// the second `AST` will essentially be dead code.
///
/// All script-defined functions in the second `AST` are first selected based on a filter
/// predicate, then overwrite similarly-named functions in the first `AST` with the
/// same number of parameters.
///
/// # Example
///
/// ```
/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
/// # #[cfg(not(feature = "no_function"))]
/// # {
/// use rhai::Engine;
///
/// let engine = Engine::new();
///
/// let ast1 = engine.compile(r#"
/// fn foo(x) { 42 + x }
/// foo(1)
/// "#)?;
///
/// let ast2 = engine.compile(r#"
/// fn foo(n) { "hello" + n }
/// fn error() { 0 }
/// foo("!")
/// "#)?;
///
/// // Merge 'ast2', picking only 'error()' but not 'foo(_)', into 'ast1'
/// let ast = ast1.merge_filtered(&ast2, |_, name, params| name == "error" && params == 0);
///
/// // 'ast' is essentially:
/// //
/// // fn foo(n) { 42 + n } // <- definition of 'ast1::foo' is not overwritten
/// // // because 'ast2::foo' is filtered away
/// // foo(1) // <- notice this will be 43 instead of "hello1",
/// // // but it is no longer the return value
/// // fn error() { 0 } // <- this function passes the filter and is merged
/// // foo("!") // <- returns "42!"
///
/// // Evaluate it
/// assert_eq!(engine.eval_ast::<String>(&ast)?, "42!");
/// # }
/// # Ok(())
/// # }
/// ```
pub fn merge_filtered(
&self,
other: &Self,
filter: impl Fn(FnAccess, &str, usize) -> bool,
) -> Self {
let Self(statements, functions) = self;
let ast = match (statements.is_empty(), other.0.is_empty()) {
(false, false) => {
let mut statements = statements.clone();
statements.extend(other.0.iter().cloned());
statements
}
(false, true) => statements.clone(),
(true, false) => other.0.clone(),
(true, true) => vec![],
};
let mut functions = functions.clone();
functions.merge_filtered(&other.1, filter);
Self::new(ast, functions)
}
/// Filter out the functions, retaining only some based on a filter predicate.
///
/// # Example
///
/// ```
/// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
/// # #[cfg(not(feature = "no_function"))]
/// # {
/// use rhai::Engine;
///
/// let engine = Engine::new();
///
/// let mut ast = engine.compile(r#"
/// fn foo(n) { n + 1 }
/// fn bar() { print("hello"); }
/// "#)?;
///
/// // Remove all functions except 'foo(_)'
/// ast.retain_functions(|_, name, params| name == "foo" && params == 1);
/// # }
/// # Ok(())
/// # }
/// ```
#[cfg(not(feature = "no_function"))]
pub fn retain_functions(&mut self, filter: impl Fn(FnAccess, &str, usize) -> bool) {
self.1.retain_functions(filter);
}
/// Clear all function definitions in the `AST`.
#[cfg(not(feature = "no_function"))]
pub fn clear_functions(&mut self) {
self.1 = Default::default();
}
/// Clear all statements in the `AST`, leaving only function definitions.
pub fn clear_statements(&mut self) {
self.0 = vec![];
}
}
impl Add<Self> for &AST {
type Output = AST;
fn add(self, rhs: Self) -> Self::Output {
self.merge(rhs)
}
}
impl AsRef<[Stmt]> for AST {
fn as_ref(&self) -> &[Stmt] {
self.statements()
}
}
impl AsRef<Module> for AST {
fn as_ref(&self) -> &Module {
self.lib()
}
}
/// A type representing the access mode of a scripted function.
#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
pub enum FnAccess {
/// Private function.
Private,
/// Public function.
Public,
}
impl fmt::Display for FnAccess {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Self::Private => write!(f, "private"),
Self::Public => write!(f, "public"),
}
}
}
/// A scripted function definition.
#[derive(Debug, Clone)]
pub struct ScriptFnDef {
/// Function name.
pub name: String,
/// Function access mode.
pub access: FnAccess,
/// Names of function parameters.
pub params: StaticVec<String>,
/// Function body.
pub body: Stmt,
/// Position of the function definition.
pub pos: Position,
}
impl fmt::Display for ScriptFnDef {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(
f,
"{}{}({})",
match self.access {
FnAccess::Public => "",
FnAccess::Private => "private ",
},
self.name,
self.params
.iter()
.map(|s| s.as_str())
.collect::<Vec<_>>()
.join(",")
)
}
}
/// `return`/`throw` statement.
#[derive(Debug, Eq, PartialEq, Hash, Clone, Copy)]
pub enum ReturnType {
/// `return` statement.
Return,
/// `throw` statement.
Exception,
}
#[derive(Clone)]
struct ParseState<'e> {
/// Reference to the scripting `Engine`.
engine: &'e Engine,
/// Encapsulates a local stack with variable names to simulate an actual runtime scope.
stack: Vec<(String, ScopeEntryType)>,
/// Encapsulates a local stack with variable names to simulate an actual runtime scope.
modules: Vec<String>,
/// Maximum levels of expression nesting.
max_expr_depth: usize,
}
impl<'e> ParseState<'e> {
/// Create a new `ParseState`.
pub fn new(engine: &'e Engine, max_expr_depth: usize) -> Self {
Self {
engine,
max_expr_depth,
stack: Default::default(),
modules: Default::default(),
}
}
/// Find a variable by name in the `ParseState`, searching in reverse.
/// The return value is the offset to be deducted from `Stack::len`,
/// i.e. the top element of the `ParseState` is offset 1.
/// Return zero when the variable name is not found in the `ParseState`.
pub fn find_var(&self, name: &str) -> Option<NonZeroUsize> {
self.stack
.iter()
.rev()
.enumerate()
.find(|(_, (n, _))| *n == name)
.and_then(|(i, _)| NonZeroUsize::new(i + 1))
}
/// Find a module by name in the `ParseState`, searching in reverse.
/// The return value is the offset to be deducted from `Stack::len`,
/// i.e. the top element of the `ParseState` is offset 1.
/// Return zero when the variable name is not found in the `ParseState`.
pub fn find_module(&self, name: &str) -> Option<NonZeroUsize> {
self.modules
.iter()
.rev()
.enumerate()
.find(|(_, n)| *n == name)
.and_then(|(i, _)| NonZeroUsize::new(i + 1))
}
}
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
/// A type that encapsulates all the settings for a particular parsing function.
struct ParseSettings {
/// Current position.
pos: Position,
/// Is the construct being parsed located at global level?
is_global: bool,
/// Is the current position inside a loop?
is_breakable: bool,
/// Is if-expression allowed?
allow_if_expr: bool,
/// Is statement-expression allowed?
allow_stmt_expr: bool,
/// Current expression nesting level.
level: usize,
}
impl ParseSettings {
/// Create a new `ParseSettings` with one higher expression level.
pub fn level_up(&self) -> Self {
Self {
level: self.level + 1,
..*self
}
}
/// Make sure that the current level of expression nesting is within the maximum limit.
pub fn ensure_level_within_max_limit(&self, limit: usize) -> Result<(), ParseError> {
if limit == 0 {
Ok(())
} else if self.level > limit {
Err(PERR::ExprTooDeep.into_err(self.pos))
} else {
Ok(())
}
}
}
/// A statement.
///
/// Each variant is at most one pointer in size (for speed),
/// with everything being allocated together in one single tuple.
#[derive(Debug, Clone)]
pub enum Stmt {
/// No-op.
Noop(Position),
/// if expr { stmt } else { stmt }
IfThenElse(Box<(Expr, Stmt, Option<Stmt>)>),
/// while expr { stmt }
While(Box<(Expr, Stmt)>),
/// loop { stmt }
Loop(Box<Stmt>),
/// for id in expr { stmt }
For(Box<(String, Expr, Stmt)>),
/// let id = expr
Let(Box<((String, Position), Option<Expr>)>),
/// const id = expr
Const(Box<((String, Position), Expr)>),
/// { stmt; ... }
Block(Box<(StaticVec<Stmt>, Position)>),
/// { stmt }
Expr(Box<Expr>),
/// continue
Continue(Position),
/// break
Break(Position),
/// return/throw
ReturnWithVal(Box<((ReturnType, Position), Option<Expr>)>),
/// import expr as module
Import(Box<(Expr, (String, Position))>),
/// expr id as name, ...
Export(Box<StaticVec<((String, Position), Option<(String, Position)>)>>),
}
impl Default for Stmt {
fn default() -> Self {
Self::Noop(Default::default())
}
}
impl Stmt {
/// Get the `Position` of this statement.
pub fn position(&self) -> Position {
match self {
Stmt::Noop(pos) | Stmt::Continue(pos) | Stmt::Break(pos) => *pos,
Stmt::Let(x) => (x.0).1,
Stmt::Const(x) => (x.0).1,
Stmt::ReturnWithVal(x) => (x.0).1,
Stmt::Block(x) => x.1,
Stmt::IfThenElse(x) => x.0.position(),
Stmt::Expr(x) => x.position(),
Stmt::While(x) => x.1.position(),
Stmt::Loop(x) => x.position(),
Stmt::For(x) => x.2.position(),
Stmt::Import(x) => (x.1).1,
Stmt::Export(x) => (x.get(0).0).1,
}
}
/// Is this statement self-terminated (i.e. no need for a semicolon terminator)?
pub fn is_self_terminated(&self) -> bool {
match self {
Stmt::IfThenElse(_)
| Stmt::While(_)
| Stmt::Loop(_)
| Stmt::For(_)
| Stmt::Block(_) => true,
// A No-op requires a semicolon in order to know it is an empty statement!
Stmt::Noop(_) => false,
Stmt::Let(_)
| Stmt::Const(_)
| Stmt::Import(_)
| Stmt::Export(_)
| Stmt::Expr(_)
| Stmt::Continue(_)
| Stmt::Break(_)
| Stmt::ReturnWithVal(_) => false,
}
}
/// Is this statement _pure_?
pub fn is_pure(&self) -> bool {
match self {
Stmt::Noop(_) => true,
Stmt::Expr(expr) => expr.is_pure(),
Stmt::IfThenElse(x) if x.2.is_some() => {
x.0.is_pure() && x.1.is_pure() && x.2.as_ref().unwrap().is_pure()
}
Stmt::IfThenElse(x) => x.1.is_pure(),
Stmt::While(x) => x.0.is_pure() && x.1.is_pure(),
Stmt::Loop(x) => x.is_pure(),
Stmt::For(x) => x.1.is_pure() && x.2.is_pure(),
Stmt::Let(_) | Stmt::Const(_) => false,
Stmt::Block(x) => x.0.iter().all(Stmt::is_pure),
Stmt::Continue(_) | Stmt::Break(_) | Stmt::ReturnWithVal(_) => false,
Stmt::Import(_) => false,
Stmt::Export(_) => false,
}
}
}
/// An expression.
///
/// Each variant is at most one pointer in size (for speed),
/// with everything being allocated together in one single tuple.
#[derive(Debug, Clone)]
pub enum Expr {
/// Integer constant.
IntegerConstant(Box<(INT, Position)>),
/// Floating-point constant.
#[cfg(not(feature = "no_float"))]
FloatConstant(Box<(FLOAT, Position)>),
/// Character constant.
CharConstant(Box<(char, Position)>),
/// String constant.
StringConstant(Box<(ImmutableString, Position)>),
/// Variable access - ((variable name, position), optional modules, hash, optional index)
Variable(
Box<(
(String, Position),
Option<Box<ModuleRef>>,
u64,
Option<NonZeroUsize>,
)>,
),
/// Property access.
Property(Box<((String, String, String), Position)>),
/// { stmt }
Stmt(Box<(Stmt, Position)>),
/// Wrapped expression - should not be optimized away.
Expr(Box<Expr>),
/// func(expr, ... ) - ((function name, native_only, position), optional modules, hash, arguments, optional default value)
/// Use `Cow<'static, str>` because a lot of operators (e.g. `==`, `>=`) are implemented as function calls
/// and the function names are predictable, so no need to allocate a new `String`.
FnCall(
Box<(
(Cow<'static, str>, bool, Position),
Option<Box<ModuleRef>>,
u64,
StaticVec<Expr>,
Option<Dynamic>,
)>,
),
/// expr op= expr
Assignment(Box<(Expr, Cow<'static, str>, Expr, Position)>),
/// lhs.rhs
Dot(Box<(Expr, Expr, Position)>),
/// expr[expr]
Index(Box<(Expr, Expr, Position)>),
/// [ expr, ... ]
Array(Box<(StaticVec<Expr>, Position)>),
/// #{ name:expr, ... }
Map(Box<(StaticVec<((ImmutableString, Position), Expr)>, Position)>),
/// lhs in rhs
In(Box<(Expr, Expr, Position)>),
/// lhs && rhs
And(Box<(Expr, Expr, Position)>),
/// lhs || rhs
Or(Box<(Expr, Expr, Position)>),
/// true
True(Position),
/// false
False(Position),
/// ()
Unit(Position),
}
impl Default for Expr {
fn default() -> Self {
Self::Unit(Default::default())
}
}
impl Expr {
/// Get the `Dynamic` value of a constant expression.
///
/// # Panics
///
/// Panics when the expression is not constant.
pub fn get_constant_value(&self) -> Dynamic {
match self {
Self::Expr(x) => x.get_constant_value(),
Self::IntegerConstant(x) => x.0.into(),
#[cfg(not(feature = "no_float"))]
Self::FloatConstant(x) => x.0.into(),
Self::CharConstant(x) => x.0.into(),
Self::StringConstant(x) => x.0.clone().into(),
Self::True(_) => true.into(),
Self::False(_) => false.into(),
Self::Unit(_) => ().into(),
#[cfg(not(feature = "no_index"))]
Self::Array(x) if x.0.iter().all(Self::is_constant) => Dynamic(Union::Array(Box::new(
x.0.iter().map(Self::get_constant_value).collect::<Vec<_>>(),
))),
#[cfg(not(feature = "no_object"))]
Self::Map(x) if x.0.iter().all(|(_, v)| v.is_constant()) => {
Dynamic(Union::Map(Box::new(
x.0.iter()
.map(|((k, _), v)| (k.clone(), v.get_constant_value()))
.collect::<HashMap<_, _>>(),
)))
}
_ => unreachable!("cannot get value of non-constant expression"),
}
}
/// Get the display value of a constant expression.
///
/// # Panics
///
/// Panics when the expression is not constant.
pub fn get_constant_str(&self) -> String {
match self {
Self::Expr(x) => x.get_constant_str(),
#[cfg(not(feature = "no_float"))]
Self::FloatConstant(x) => x.0.to_string(),
Self::IntegerConstant(x) => x.0.to_string(),
Self::CharConstant(x) => x.0.to_string(),
Self::StringConstant(_) => "string".to_string(),
Self::True(_) => "true".to_string(),
Self::False(_) => "false".to_string(),
Self::Unit(_) => "()".to_string(),
Self::Array(x) if x.0.iter().all(Self::is_constant) => "array".to_string(),
_ => unreachable!("cannot get value of non-constant expression"),
}
}
/// Get the `Position` of the expression.
pub fn position(&self) -> Position {
match self {
Self::Expr(x) => x.position(),
#[cfg(not(feature = "no_float"))]
Self::FloatConstant(x) => x.1,
Self::IntegerConstant(x) => x.1,
Self::CharConstant(x) => x.1,
Self::StringConstant(x) => x.1,
Self::Array(x) => x.1,
Self::Map(x) => x.1,
Self::Property(x) => x.1,
Self::Stmt(x) => x.1,
Self::Variable(x) => (x.0).1,
Self::FnCall(x) => (x.0).2,
Self::Assignment(x) => x.0.position(),
Self::And(x) | Self::Or(x) | Self::In(x) => x.2,
Self::True(pos) | Self::False(pos) | Self::Unit(pos) => *pos,
Self::Dot(x) | Self::Index(x) => x.0.position(),
}
}
/// Override the `Position` of the expression.
pub(crate) fn set_position(mut self, new_pos: Position) -> Self {
match &mut self {
Self::Expr(ref mut x) => {
let expr = mem::take(x);
*x = Box::new(expr.set_position(new_pos));
}
#[cfg(not(feature = "no_float"))]
Self::FloatConstant(x) => x.1 = new_pos,
Self::IntegerConstant(x) => x.1 = new_pos,
Self::CharConstant(x) => x.1 = new_pos,
Self::StringConstant(x) => x.1 = new_pos,
Self::Array(x) => x.1 = new_pos,
Self::Map(x) => x.1 = new_pos,
Self::Variable(x) => (x.0).1 = new_pos,
Self::Property(x) => x.1 = new_pos,
Self::Stmt(x) => x.1 = new_pos,
Self::FnCall(x) => (x.0).2 = new_pos,
Self::And(x) => x.2 = new_pos,
Self::Or(x) => x.2 = new_pos,
Self::In(x) => x.2 = new_pos,
Self::True(pos) => *pos = new_pos,
Self::False(pos) => *pos = new_pos,
Self::Unit(pos) => *pos = new_pos,
Self::Assignment(x) => x.3 = new_pos,
Self::Dot(x) => x.2 = new_pos,
Self::Index(x) => x.2 = new_pos,
}
self
}
/// Is the expression pure?
///
/// A pure expression has no side effects.
pub fn is_pure(&self) -> bool {
match self {
Self::Expr(x) => x.is_pure(),
Self::Array(x) => x.0.iter().all(Self::is_pure),
Self::Index(x) | Self::And(x) | Self::Or(x) | Self::In(x) => {
let (lhs, rhs, _) = x.as_ref();
lhs.is_pure() && rhs.is_pure()
}
Self::Stmt(x) => x.0.is_pure(),
Self::Variable(_) => true,
_ => self.is_constant(),
}
}
/// Is the expression a constant?
pub fn is_constant(&self) -> bool {
match self {
Self::Expr(x) => x.is_constant(),
#[cfg(not(feature = "no_float"))]
Self::FloatConstant(_) => true,
Self::IntegerConstant(_)
| Self::CharConstant(_)
| Self::StringConstant(_)
| Self::True(_)
| Self::False(_)
| Self::Unit(_) => true,
// An array literal is constant if all items are constant
Self::Array(x) => x.0.iter().all(Self::is_constant),
// An map literal is constant if all items are constant
Self::Map(x) => x.0.iter().map(|(_, expr)| expr).all(Self::is_constant),
// Check in expression
Self::In(x) => match (&x.0, &x.1) {
(Self::StringConstant(_), Self::StringConstant(_))
| (Self::CharConstant(_), Self::StringConstant(_)) => true,
_ => false,
},
_ => false,
}
}
/// Is a particular token allowed as a postfix operator to this expression?
pub fn is_valid_postfix(&self, token: &Token) -> bool {
match self {
Self::Expr(x) => x.is_valid_postfix(token),
#[cfg(not(feature = "no_float"))]
Self::FloatConstant(_) => false,
Self::IntegerConstant(_)
| Self::CharConstant(_)
| Self::In(_)
| Self::And(_)
| Self::Or(_)
| Self::True(_)
| Self::False(_)
| Self::Unit(_)
| Self::Assignment(_) => false,
Self::StringConstant(_)
| Self::Stmt(_)
| Self::FnCall(_)
| Self::Dot(_)
| Self::Index(_)
| Self::Array(_)
| Self::Map(_) => match token {
#[cfg(not(feature = "no_index"))]
Token::LeftBracket => true,
_ => false,
},
Self::Variable(_) => match token {
#[cfg(not(feature = "no_index"))]
Token::LeftBracket => true,
Token::LeftParen => true,
Token::DoubleColon => true,
_ => false,
},
Self::Property(_) => match token {
#[cfg(not(feature = "no_index"))]
Token::LeftBracket => true,
Token::LeftParen => true,
_ => false,
},
}
}
/// Convert a `Variable` into a `Property`. All other variants are untouched.
pub(crate) fn into_property(self) -> Self {
match self {
Self::Variable(x) if x.1.is_none() => {
let (name, pos) = x.0;
let getter = make_getter(&name);
let setter = make_setter(&name);
Self::Property(Box::new(((name.clone(), getter, setter), pos)))
}
_ => self,
}
}
}
/// Consume a particular token, checking that it is the expected one.
fn eat_token(input: &mut TokenStream, token: Token) -> Position {
let (t, pos) = input.next().unwrap();
if t != token {
unreachable!(
"expecting {} (found {}) at {}",
token.syntax(),
t.syntax(),
pos
);
}
pos
}
/// Match a particular token, consuming it if matched.
fn match_token(input: &mut TokenStream, token: Token) -> Result<bool, ParseError> {
let (t, _) = input.peek().unwrap();
if *t == token {
eat_token(input, token);
Ok(true)
} else {
Ok(false)
}
}
/// Parse ( expr )
fn parse_paren_expr(
input: &mut TokenStream,
state: &mut ParseState,
settings: ParseSettings,
) -> Result<Expr, ParseError> {
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
if match_token(input, Token::RightParen)? {
return Ok(Expr::Unit(settings.pos));
}
let expr = parse_expr(input, state, settings.level_up())?;
match input.next().unwrap() {
// ( xxx )
(Token::RightParen, _) => Ok(expr),
// ( <error>
(Token::LexError(err), pos) => return Err(err.into_err(pos)),
// ( xxx ???
(_, pos) => Err(PERR::MissingToken(
Token::RightParen.into(),
"for a matching ( in this expression".into(),
)
.into_err(pos)),
}
}
/// Parse a function call.
fn parse_call_expr(
input: &mut TokenStream,
state: &mut ParseState,
id: String,
mut modules: Option<Box<ModuleRef>>,
settings: ParseSettings,
) -> Result<Expr, ParseError> {
let (token, token_pos) = input.peek().unwrap();
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
let mut args = StaticVec::new();
match token {
// id( <EOF>
Token::EOF => {
return Err(PERR::MissingToken(
Token::RightParen.into(),
format!("to close the arguments list of this function call '{}'", id),
)
.into_err(*token_pos))
}
// id( <error>
Token::LexError(err) => return Err(err.into_err(*token_pos)),
// id()
Token::RightParen => {
eat_token(input, Token::RightParen);
let hash_script = if let Some(modules) = modules.as_mut() {
modules.set_index(state.find_module(&modules.get(0).0));
// Rust functions are indexed in two steps:
// 1) Calculate a hash in a similar manner to script-defined functions,
// i.e. qualifiers + function name + number of arguments.
// 2) Calculate a second hash with no qualifiers, empty function name,
// zero number of arguments, and the actual list of argument `TypeId`'s.
// 3) The final hash is the XOR of the two hashes.
let qualifiers = modules.iter().map(|(m, _)| m.as_str());
calc_fn_hash(qualifiers, &id, 0, empty())
} else {
// Qualifiers (none) + function name + no parameters.
calc_fn_hash(empty(), &id, 0, empty())
};
return Ok(Expr::FnCall(Box::new((
(id.into(), false, settings.pos),
modules,
hash_script,
args,
None,
))));
}
// id...
_ => (),
}
let settings = settings.level_up();
loop {
match input.peek().unwrap() {
// id(...args, ) - handle trailing comma
(Token::RightParen, _) => (),
_ => args.push(parse_expr(input, state, settings)?),
}
match input.peek().unwrap() {
// id(...args)
(Token::RightParen, _) => {
eat_token(input, Token::RightParen);
let hash_script = if let Some(modules) = modules.as_mut() {
modules.set_index(state.find_module(&modules.get(0).0));
// Rust functions are indexed in two steps:
// 1) Calculate a hash in a similar manner to script-defined functions,
// i.e. qualifiers + function name + number of arguments.
// 2) Calculate a second hash with no qualifiers, empty function name,
// zero number of arguments, and the actual list of argument `TypeId`'s.
// 3) The final hash is the XOR of the two hashes.
let qualifiers = modules.iter().map(|(m, _)| m.as_str());
calc_fn_hash(qualifiers, &id, args.len(), empty())
} else {
// Qualifiers (none) + function name + number of arguments.
calc_fn_hash(empty(), &id, args.len(), empty())
};
return Ok(Expr::FnCall(Box::new((
(id.into(), false, settings.pos),
modules,
hash_script,
args,
None,
))));
}
// id(...args,
(Token::Comma, _) => {
eat_token(input, Token::Comma);
}
// id(...args <EOF>
(Token::EOF, pos) => {
return Err(PERR::MissingToken(
Token::RightParen.into(),
format!("to close the arguments list of this function call '{}'", id),
)
.into_err(*pos))
}
// id(...args <error>
(Token::LexError(err), pos) => return Err(err.into_err(*pos)),
// id(...args ???
(_, pos) => {
return Err(PERR::MissingToken(
Token::Comma.into(),
format!("to separate the arguments to function call '{}'", id),
)
.into_err(*pos))
}
}
}
}
/// Parse an indexing chain.
/// Indexing binds to the right, so this call parses all possible levels of indexing following in the input.
fn parse_index_chain(
input: &mut TokenStream,
state: &mut ParseState,
lhs: Expr,
mut settings: ParseSettings,
) -> Result<Expr, ParseError> {
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
let idx_expr = parse_expr(input, state, settings.level_up())?;
// Check type of indexing - must be integer or string
match &idx_expr {
// lhs[int]
Expr::IntegerConstant(x) if x.0 < 0 => {
return Err(PERR::MalformedIndexExpr(format!(
"Array access expects non-negative index: {} < 0",
x.0
))
.into_err(x.1))
}
Expr::IntegerConstant(x) => match lhs {
Expr::Array(_) | Expr::StringConstant(_) => (),
Expr::Map(_) => {
return Err(PERR::MalformedIndexExpr(
"Object map access expects string index, not a number".into(),
)
.into_err(x.1))
}
#[cfg(not(feature = "no_float"))]
Expr::FloatConstant(_) => {
return Err(PERR::MalformedIndexExpr(
"Only arrays, object maps and strings can be indexed".into(),
)
.into_err(lhs.position()))
}
Expr::CharConstant(_)
| Expr::Assignment(_)
| Expr::And(_)
| Expr::Or(_)
| Expr::In(_)
| Expr::True(_)
| Expr::False(_)
| Expr::Unit(_) => {
return Err(PERR::MalformedIndexExpr(
"Only arrays, object maps and strings can be indexed".into(),
)
.into_err(lhs.position()))
}
_ => (),
},
// lhs[string]
Expr::StringConstant(x) => match lhs {
Expr::Map(_) => (),
Expr::Array(_) | Expr::StringConstant(_) => {
return Err(PERR::MalformedIndexExpr(
"Array or string expects numeric index, not a string".into(),
)
.into_err(x.1))
}
#[cfg(not(feature = "no_float"))]
Expr::FloatConstant(_) => {
return Err(PERR::MalformedIndexExpr(
"Only arrays, object maps and strings can be indexed".into(),
)
.into_err(lhs.position()))
}
Expr::CharConstant(_)
| Expr::Assignment(_)
| Expr::And(_)
| Expr::Or(_)
| Expr::In(_)
| Expr::True(_)
| Expr::False(_)
| Expr::Unit(_) => {
return Err(PERR::MalformedIndexExpr(
"Only arrays, object maps and strings can be indexed".into(),
)
.into_err(lhs.position()))
}
_ => (),
},
// lhs[float]
#[cfg(not(feature = "no_float"))]
x @ Expr::FloatConstant(_) => {
return Err(PERR::MalformedIndexExpr(
"Array access expects integer index, not a float".into(),
)
.into_err(x.position()))
}
// lhs[char]
x @ Expr::CharConstant(_) => {
return Err(PERR::MalformedIndexExpr(
"Array access expects integer index, not a character".into(),
)
.into_err(x.position()))
}
// lhs[??? = ??? ]
x @ Expr::Assignment(_) => {
return Err(PERR::MalformedIndexExpr(
"Array access expects integer index, not an assignment".into(),
)
.into_err(x.position()))
}
// lhs[()]
x @ Expr::Unit(_) => {
return Err(PERR::MalformedIndexExpr(
"Array access expects integer index, not ()".into(),
)
.into_err(x.position()))
}
// lhs[??? && ???], lhs[??? || ???], lhs[??? in ???]
x @ Expr::And(_) | x @ Expr::Or(_) | x @ Expr::In(_) => {
return Err(PERR::MalformedIndexExpr(
"Array access expects integer index, not a boolean".into(),
)
.into_err(x.position()))
}
// lhs[true], lhs[false]
x @ Expr::True(_) | x @ Expr::False(_) => {
return Err(PERR::MalformedIndexExpr(
"Array access expects integer index, not a boolean".into(),
)
.into_err(x.position()))
}
// All other expressions
_ => (),
}
// Check if there is a closing bracket
match input.peek().unwrap() {
(Token::RightBracket, _) => {
eat_token(input, Token::RightBracket);
// Any more indexing following?
match input.peek().unwrap() {
// If another indexing level, right-bind it
(Token::LeftBracket, _) => {
let prev_pos = settings.pos;
settings.pos = eat_token(input, Token::LeftBracket);
// Recursively parse the indexing chain, right-binding each
let idx_expr = parse_index_chain(input, state, idx_expr, settings.level_up())?;
// Indexing binds to right
Ok(Expr::Index(Box::new((lhs, idx_expr, prev_pos))))
}
// Otherwise terminate the indexing chain
_ => {
match idx_expr {
// Terminate with an `Expr::Expr` wrapper to prevent the last index expression
// inside brackets to be mis-parsed as another level of indexing, or a
// dot expression/function call to be mis-parsed as following the indexing chain.
Expr::Index(_) | Expr::Dot(_) | Expr::FnCall(_) => Ok(Expr::Index(
Box::new((lhs, Expr::Expr(Box::new(idx_expr)), settings.pos)),
)),
_ => Ok(Expr::Index(Box::new((lhs, idx_expr, settings.pos)))),
}
}
}
}
(Token::LexError(err), pos) => return Err(err.into_err(*pos)),
(_, pos) => Err(PERR::MissingToken(
Token::RightBracket.into(),
"for a matching [ in this index expression".into(),
)
.into_err(*pos)),
}
}
/// Parse an array literal.
fn parse_array_literal(
input: &mut TokenStream,
state: &mut ParseState,
settings: ParseSettings,
) -> Result<Expr, ParseError> {
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
let mut arr = StaticVec::new();
while !input.peek().unwrap().0.is_eof() {
if state.engine.max_array_size > 0 && arr.len() >= state.engine.max_array_size {
return Err(PERR::LiteralTooLarge(
"Size of array literal".to_string(),
state.engine.max_array_size,
)
.into_err(input.peek().unwrap().1));
}
match input.peek().unwrap() {
(Token::RightBracket, _) => {
eat_token(input, Token::RightBracket);
break;
}
_ => {
let expr = parse_expr(input, state, settings.level_up())?;
arr.push(expr);
}
}
match input.peek().unwrap() {
(Token::Comma, _) => {
eat_token(input, Token::Comma);
}
(Token::RightBracket, _) => (),
(Token::EOF, pos) => {
return Err(PERR::MissingToken(
Token::RightBracket.into(),
"to end this array literal".into(),
)
.into_err(*pos))
}
(Token::LexError(err), pos) => return Err(err.into_err(*pos)),
(_, pos) => {
return Err(PERR::MissingToken(
Token::Comma.into(),
"to separate the items of this array literal".into(),
)
.into_err(*pos))
}
};
}
Ok(Expr::Array(Box::new((arr, settings.pos))))
}
/// Parse a map literal.
fn parse_map_literal(
input: &mut TokenStream,
state: &mut ParseState,
settings: ParseSettings,
) -> Result<Expr, ParseError> {
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
let mut map = StaticVec::new();
while !input.peek().unwrap().0.is_eof() {
const MISSING_RBRACE: &str = "to end this object map literal";
match input.peek().unwrap() {
(Token::RightBrace, _) => {
eat_token(input, Token::RightBrace);
break;
}
_ => {
let (name, pos) = match input.next().unwrap() {
(Token::Identifier(s), pos) => (s, pos),
(Token::StringConstant(s), pos) => (s, pos),
(Token::LexError(err), pos) => return Err(err.into_err(pos)),
(_, pos) if map.is_empty() => {
return Err(PERR::MissingToken(
Token::RightBrace.into(),
MISSING_RBRACE.into(),
)
.into_err(pos))
}
(Token::EOF, pos) => {
return Err(PERR::MissingToken(
Token::RightBrace.into(),
MISSING_RBRACE.into(),
)
.into_err(pos))
}
(_, pos) => return Err(PERR::PropertyExpected.into_err(pos)),
};
match input.next().unwrap() {
(Token::Colon, _) => (),
(Token::LexError(err), pos) => return Err(err.into_err(pos)),
(_, pos) => {
return Err(PERR::MissingToken(
Token::Colon.into(),
format!(
"to follow the property '{}' in this object map literal",
name
),
)
.into_err(pos))
}
};
if state.engine.max_map_size > 0 && map.len() >= state.engine.max_map_size {
return Err(PERR::LiteralTooLarge(
"Number of properties in object map literal".to_string(),
state.engine.max_map_size,
)
.into_err(input.peek().unwrap().1));
}
let expr = parse_expr(input, state, settings.level_up())?;
map.push(((Into::<ImmutableString>::into(name), pos), expr));
}
}
match input.peek().unwrap() {
(Token::Comma, _) => {
eat_token(input, Token::Comma);
}
(Token::RightBrace, _) => (),
(Token::Identifier(_), pos) => {
return Err(PERR::MissingToken(
Token::Comma.into(),
"to separate the items of this object map literal".into(),
)
.into_err(*pos))
}
(Token::LexError(err), pos) => return Err(err.into_err(*pos)),
(_, pos) => {
return Err(
PERR::MissingToken(Token::RightBrace.into(), MISSING_RBRACE.into())
.into_err(*pos),
)
}
}
}
// Check for duplicating properties
map.iter()
.enumerate()
.try_for_each(|(i, ((k1, _), _))| {
map.iter()
.skip(i + 1)
.find(|((k2, _), _)| k2 == k1)
.map_or_else(|| Ok(()), |((k2, pos), _)| Err((k2, *pos)))
})
.map_err(|(key, pos)| PERR::DuplicatedProperty(key.to_string()).into_err(pos))?;
Ok(Expr::Map(Box::new((map, settings.pos))))
}
/// Parse a primary expression.
fn parse_primary(
input: &mut TokenStream,
state: &mut ParseState,
mut settings: ParseSettings,
) -> Result<Expr, ParseError> {
let (token, token_pos) = input.peek().unwrap();
settings.pos = *token_pos;
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
let (token, _) = match token {
// { - block statement as expression
Token::LeftBrace if settings.allow_stmt_expr => {
return parse_block(input, state, settings.level_up())
.map(|block| Expr::Stmt(Box::new((block, settings.pos))))
}
Token::EOF => return Err(PERR::UnexpectedEOF.into_err(settings.pos)),
_ => input.next().unwrap(),
};
let mut root_expr = match token {
Token::IntegerConstant(x) => Expr::IntegerConstant(Box::new((x, settings.pos))),
#[cfg(not(feature = "no_float"))]
Token::FloatConstant(x) => Expr::FloatConstant(Box::new((x, settings.pos))),
Token::CharConstant(c) => Expr::CharConstant(Box::new((c, settings.pos))),
Token::StringConstant(s) => Expr::StringConstant(Box::new((s.into(), settings.pos))),
Token::Identifier(s) => {
let index = state.find_var(&s);
Expr::Variable(Box::new(((s, settings.pos), None, 0, index)))
}
Token::LeftParen => parse_paren_expr(input, state, settings.level_up())?,
#[cfg(not(feature = "no_index"))]
Token::LeftBracket => parse_array_literal(input, state, settings.level_up())?,
#[cfg(not(feature = "no_object"))]
Token::MapStart => parse_map_literal(input, state, settings.level_up())?,
Token::True => Expr::True(settings.pos),
Token::False => Expr::False(settings.pos),
Token::LexError(err) => return Err(err.into_err(settings.pos)),
_ => {
return Err(
PERR::BadInput(format!("Unexpected '{}'", token.syntax())).into_err(settings.pos)
)
}
};
// Tail processing all possible postfix operators
loop {
let (token, _) = input.peek().unwrap();
if !root_expr.is_valid_postfix(token) {
break;
}
let (token, token_pos) = input.next().unwrap();
settings.pos = token_pos;
root_expr = match (root_expr, token) {
// Function call
(Expr::Variable(x), Token::LeftParen) => {
let ((name, pos), modules, _, _) = *x;
settings.pos = pos;
parse_call_expr(input, state, name, modules, settings.level_up())?
}
(Expr::Property(_), _) => unreachable!(),
// module access
(Expr::Variable(x), Token::DoubleColon) => match input.next().unwrap() {
(Token::Identifier(id2), pos2) => {
let ((name, pos), mut modules, _, index) = *x;
if let Some(ref mut modules) = modules {
modules.push((name, pos));
} else {
let mut m: ModuleRef = Default::default();
m.push((name, pos));
modules = Some(Box::new(m));
}
Expr::Variable(Box::new(((id2, pos2), modules, 0, index)))
}
(_, pos2) => return Err(PERR::VariableExpected.into_err(pos2)),
},
// Indexing
#[cfg(not(feature = "no_index"))]
(expr, Token::LeftBracket) => {
parse_index_chain(input, state, expr, settings.level_up())?
}
// Unknown postfix operator
(expr, token) => unreachable!(
"unknown postfix operator '{}' for {:?}",
token.syntax(),
expr
),
}
}
match &mut root_expr {
// Cache the hash key for module-qualified variables
Expr::Variable(x) if x.1.is_some() => {
let ((name, _), modules, hash, _) = x.as_mut();
let modules = modules.as_mut().unwrap();
// Qualifiers + variable name
*hash = calc_fn_hash(modules.iter().map(|(v, _)| v.as_str()), name, 0, empty());
modules.set_index(state.find_module(&modules.get(0).0));
}
_ => (),
}
Ok(root_expr)
}
/// Parse a potential unary operator.
fn parse_unary(
input: &mut TokenStream,
state: &mut ParseState,
mut settings: ParseSettings,
) -> Result<Expr, ParseError> {
let (token, token_pos) = input.peek().unwrap();
settings.pos = *token_pos;
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
match token {
// If statement is allowed to act as expressions
Token::If if settings.allow_if_expr => Ok(Expr::Stmt(Box::new((
parse_if(input, state, settings.level_up())?,
settings.pos,
)))),
// -expr
Token::UnaryMinus => {
let pos = eat_token(input, Token::UnaryMinus);
match parse_unary(input, state, settings.level_up())? {
// Negative integer
Expr::IntegerConstant(x) => {
let (num, pos) = *x;
num.checked_neg()
.map(|i| Expr::IntegerConstant(Box::new((i, pos))))
.or_else(|| {
#[cfg(not(feature = "no_float"))]
return Some(Expr::FloatConstant(Box::new((-(x.0 as FLOAT), pos))));
#[cfg(feature = "no_float")]
return None;
})
.ok_or_else(|| LexError::MalformedNumber(format!("-{}", x.0)).into_err(pos))
}
// Negative float
#[cfg(not(feature = "no_float"))]
Expr::FloatConstant(x) => Ok(Expr::FloatConstant(Box::new((-x.0, x.1)))),
// Call negative function
expr => {
let op = "-";
let hash = calc_fn_hash(empty(), op, 2, empty());
let mut args = StaticVec::new();
args.push(expr);
Ok(Expr::FnCall(Box::new((
(op.into(), true, pos),
None,
hash,
args,
None,
))))
}
}
}
// +expr
Token::UnaryPlus => {
eat_token(input, Token::UnaryPlus);
parse_unary(input, state, settings.level_up())
}
// !expr
Token::Bang => {
let pos = eat_token(input, Token::Bang);
let mut args = StaticVec::new();
let expr = parse_primary(input, state, settings.level_up())?;
args.push(expr);
let op = "!";
let hash = calc_fn_hash(empty(), op, 2, empty());
Ok(Expr::FnCall(Box::new((
(op.into(), true, pos),
None,
hash,
args,
Some(false.into()), // NOT operator, when operating on invalid operand, defaults to false
))))
}
// <EOF>
Token::EOF => Err(PERR::UnexpectedEOF.into_err(settings.pos)),
// All other tokens
_ => parse_primary(input, state, settings.level_up()),
}
}
fn make_assignment_stmt<'a>(
fn_name: Cow<'static, str>,
state: &mut ParseState,
lhs: Expr,
rhs: Expr,
pos: Position,
) -> Result<Expr, ParseError> {
match &lhs {
// var (non-indexed) = rhs
Expr::Variable(x) if x.3.is_none() => {
Ok(Expr::Assignment(Box::new((lhs, fn_name.into(), rhs, pos))))
}
// var (indexed) = rhs
Expr::Variable(x) => {
let ((name, name_pos), _, _, index) = x.as_ref();
match state.stack[(state.stack.len() - index.unwrap().get())].1 {
ScopeEntryType::Normal => {
Ok(Expr::Assignment(Box::new((lhs, fn_name.into(), rhs, pos))))
}
// Constant values cannot be assigned to
ScopeEntryType::Constant => {
Err(PERR::AssignmentToConstant(name.clone()).into_err(*name_pos))
}
}
}
// xxx[???] = rhs, xxx.??? = rhs
Expr::Index(x) | Expr::Dot(x) => match &x.0 {
// var[???] (non-indexed) = rhs, var.??? (non-indexed) = rhs
Expr::Variable(x) if x.3.is_none() => {
Ok(Expr::Assignment(Box::new((lhs, fn_name.into(), rhs, pos))))
}
// var[???] (indexed) = rhs, var.??? (indexed) = rhs
Expr::Variable(x) => {
let ((name, name_pos), _, _, index) = x.as_ref();
match state.stack[(state.stack.len() - index.unwrap().get())].1 {
ScopeEntryType::Normal => {
Ok(Expr::Assignment(Box::new((lhs, fn_name.into(), rhs, pos))))
}
// Constant values cannot be assigned to
ScopeEntryType::Constant => {
Err(PERR::AssignmentToConstant(name.clone()).into_err(*name_pos))
}
}
}
// expr[???] = rhs, expr.??? = rhs
_ => Err(PERR::AssignmentToCopy.into_err(x.0.position())),
},
// const_expr = rhs
expr if expr.is_constant() => {
Err(PERR::AssignmentToConstant("".into()).into_err(lhs.position()))
}
// ??? && ??? = rhs, ??? || ??? = rhs
Expr::And(_) | Expr::Or(_) => {
Err(PERR::BadInput("Possibly a typo of '=='?".to_string()).into_err(pos))
}
// expr = rhs
_ => Err(PERR::AssignmentToCopy.into_err(lhs.position())),
}
}
/// Parse an operator-assignment expression.
fn parse_op_assignment_stmt(
input: &mut TokenStream,
state: &mut ParseState,
lhs: Expr,
mut settings: ParseSettings,
) -> Result<Expr, ParseError> {
let (token, token_pos) = input.peek().unwrap();
settings.pos = *token_pos;
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
let op = match token {
Token::Equals => "".into(),
Token::PlusAssign
| Token::MinusAssign
| Token::MultiplyAssign
| Token::DivideAssign
| Token::LeftShiftAssign
| Token::RightShiftAssign
| Token::ModuloAssign
| Token::PowerOfAssign
| Token::AndAssign
| Token::OrAssign
| Token::XOrAssign => token.syntax(),
_ => return Ok(lhs),
};
let (_, pos) = input.next().unwrap();
let rhs = parse_expr(input, state, settings.level_up())?;
make_assignment_stmt(op, state, lhs, rhs, pos)
}
/// Make a dot expression.
fn make_dot_expr(lhs: Expr, rhs: Expr, op_pos: Position) -> Result<Expr, ParseError> {
Ok(match (lhs, rhs) {
// idx_lhs[idx_expr].rhs
// Attach dot chain to the bottom level of indexing chain
(Expr::Index(x), rhs) => {
let (idx_lhs, idx_expr, pos) = *x;
Expr::Index(Box::new((
idx_lhs,
make_dot_expr(idx_expr, rhs, op_pos)?,
pos,
)))
}
// lhs.id
(lhs, Expr::Variable(x)) if x.1.is_none() => {
let (name, pos) = x.0;
let getter = make_getter(&name);
let setter = make_setter(&name);
let rhs = Expr::Property(Box::new(((name, getter, setter), pos)));
Expr::Dot(Box::new((lhs, rhs, op_pos)))
}
// lhs.module::id - syntax error
(_, Expr::Variable(x)) if x.1.is_some() => {
return Err(PERR::PropertyExpected.into_err(x.1.unwrap().get(0).1));
}
// lhs.prop
(lhs, prop @ Expr::Property(_)) => Expr::Dot(Box::new((lhs, prop, op_pos))),
// lhs.dot_lhs.dot_rhs
(lhs, Expr::Dot(x)) => {
let (dot_lhs, dot_rhs, pos) = *x;
Expr::Dot(Box::new((
lhs,
Expr::Dot(Box::new((dot_lhs.into_property(), dot_rhs, pos))),
op_pos,
)))
}
// lhs.idx_lhs[idx_rhs]
(lhs, Expr::Index(x)) => {
let (dot_lhs, dot_rhs, pos) = *x;
Expr::Dot(Box::new((
lhs,
Expr::Index(Box::new((dot_lhs.into_property(), dot_rhs, pos))),
op_pos,
)))
}
// lhs.func()
(lhs, func @ Expr::FnCall(_)) => Expr::Dot(Box::new((lhs, func, op_pos))),
// lhs.rhs
(_, rhs) => return Err(PERR::PropertyExpected.into_err(rhs.position())),
})
}
/// Make an 'in' expression.
fn make_in_expr(lhs: Expr, rhs: Expr, op_pos: Position) -> Result<Expr, ParseError> {
match (&lhs, &rhs) {
(_, x @ Expr::IntegerConstant(_))
| (_, x @ Expr::And(_))
| (_, x @ Expr::Or(_))
| (_, x @ Expr::In(_))
| (_, x @ Expr::Assignment(_))
| (_, x @ Expr::True(_))
| (_, x @ Expr::False(_))
| (_, x @ Expr::Unit(_)) => {
return Err(PERR::MalformedInExpr(
"'in' expression expects a string, array or object map".into(),
)
.into_err(x.position()))
}
#[cfg(not(feature = "no_float"))]
(_, x @ Expr::FloatConstant(_)) => {
return Err(PERR::MalformedInExpr(
"'in' expression expects a string, array or object map".into(),
)
.into_err(x.position()))
}
// "xxx" in "xxxx", 'x' in "xxxx" - OK!
(Expr::StringConstant(_), Expr::StringConstant(_))
| (Expr::CharConstant(_), Expr::StringConstant(_)) => (),
// 123.456 in "xxxx"
#[cfg(not(feature = "no_float"))]
(x @ Expr::FloatConstant(_), Expr::StringConstant(_)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for a string expects a string, not a float".into(),
)
.into_err(x.position()))
}
// 123 in "xxxx"
(x @ Expr::IntegerConstant(_), Expr::StringConstant(_)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for a string expects a string, not a number".into(),
)
.into_err(x.position()))
}
// (??? && ???) in "xxxx", (??? || ???) in "xxxx", (??? in ???) in "xxxx",
// true in "xxxx", false in "xxxx"
(x @ Expr::And(_), Expr::StringConstant(_))
| (x @ Expr::Or(_), Expr::StringConstant(_))
| (x @ Expr::In(_), Expr::StringConstant(_))
| (x @ Expr::True(_), Expr::StringConstant(_))
| (x @ Expr::False(_), Expr::StringConstant(_)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for a string expects a string, not a boolean".into(),
)
.into_err(x.position()))
}
// [???, ???, ???] in "xxxx"
(x @ Expr::Array(_), Expr::StringConstant(_)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for a string expects a string, not an array".into(),
)
.into_err(x.position()))
}
// #{...} in "xxxx"
(x @ Expr::Map(_), Expr::StringConstant(_)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for a string expects a string, not an object map".into(),
)
.into_err(x.position()))
}
// (??? = ???) in "xxxx"
(x @ Expr::Assignment(_), Expr::StringConstant(_)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for a string expects a string, not an assignment".into(),
)
.into_err(x.position()))
}
// () in "xxxx"
(x @ Expr::Unit(_), Expr::StringConstant(_)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for a string expects a string, not ()".into(),
)
.into_err(x.position()))
}
// "xxx" in #{...}, 'x' in #{...} - OK!
(Expr::StringConstant(_), Expr::Map(_)) | (Expr::CharConstant(_), Expr::Map(_)) => (),
// 123.456 in #{...}
#[cfg(not(feature = "no_float"))]
(x @ Expr::FloatConstant(_), Expr::Map(_)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for an object map expects a string, not a float".into(),
)
.into_err(x.position()))
}
// 123 in #{...}
(x @ Expr::IntegerConstant(_), Expr::Map(_)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for an object map expects a string, not a number".into(),
)
.into_err(x.position()))
}
// (??? && ???) in #{...}, (??? || ???) in #{...}, (??? in ???) in #{...},
// true in #{...}, false in #{...}
(x @ Expr::And(_), Expr::Map(_))
| (x @ Expr::Or(_), Expr::Map(_))
| (x @ Expr::In(_), Expr::Map(_))
| (x @ Expr::True(_), Expr::Map(_))
| (x @ Expr::False(_), Expr::Map(_)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for an object map expects a string, not a boolean".into(),
)
.into_err(x.position()))
}
// [???, ???, ???] in #{..}
(x @ Expr::Array(_), Expr::Map(_)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for an object map expects a string, not an array".into(),
)
.into_err(x.position()))
}
// #{...} in #{..}
(x @ Expr::Map(_), Expr::Map(_)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for an object map expects a string, not an object map".into(),
)
.into_err(x.position()))
}
// (??? = ???) in #{...}
(x @ Expr::Assignment(_), Expr::Map(_)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for an object map expects a string, not an assignment".into(),
)
.into_err(x.position()))
}
// () in #{...}
(x @ Expr::Unit(_), Expr::Map(_)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for an object map expects a string, not ()".into(),
)
.into_err(x.position()))
}
_ => (),
}
Ok(Expr::In(Box::new((lhs, rhs, op_pos))))
}
/// Parse a binary expression.
fn parse_binary_op(
input: &mut TokenStream,
state: &mut ParseState,
parent_precedence: u8,
lhs: Expr,
mut settings: ParseSettings,
) -> Result<Expr, ParseError> {
settings.pos = lhs.position();
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
let mut root = lhs;
loop {
let (current_op, _) = input.peek().unwrap();
let custom = state.engine.custom_keywords.as_ref();
let precedence = current_op.precedence(custom);
let bind_right = current_op.is_bind_right();
// Bind left to the parent lhs expression if precedence is higher
// If same precedence, then check if the operator binds right
if precedence < parent_precedence || (precedence == parent_precedence && !bind_right) {
return Ok(root);
}
let (op_token, pos) = input.next().unwrap();
let rhs = parse_unary(input, state, settings)?;
let next_precedence = input.peek().unwrap().0.precedence(custom);
// Bind to right if the next operator has higher precedence
// If same precedence, then check if the operator binds right
let rhs = if (precedence == next_precedence && bind_right) || precedence < next_precedence {
parse_binary_op(input, state, precedence, rhs, settings)?
} else {
// Otherwise bind to left (even if next operator has the same precedence)
rhs
};
settings = settings.level_up();
settings.pos = pos;
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
let cmp_def = Some(false.into());
let op = op_token.syntax();
let hash = calc_fn_hash(empty(), &op, 2, empty());
let op = (op, true, pos);
let mut args = StaticVec::new();
args.push(root);
args.push(rhs);
root = match op_token {
Token::Plus
| Token::Minus
| Token::Multiply
| Token::Divide
| Token::LeftShift
| Token::RightShift
| Token::Modulo
| Token::PowerOf
| Token::Ampersand
| Token::Pipe
| Token::XOr => Expr::FnCall(Box::new((op, None, hash, args, None))),
// '!=' defaults to true when passed invalid operands
Token::NotEqualsTo => Expr::FnCall(Box::new((op, None, hash, args, Some(true.into())))),
// Comparison operators default to false when passed invalid operands
Token::EqualsTo
| Token::LessThan
| Token::LessThanEqualsTo
| Token::GreaterThan
| Token::GreaterThanEqualsTo => Expr::FnCall(Box::new((op, None, hash, args, cmp_def))),
Token::Or => {
let rhs = args.pop();
let current_lhs = args.pop();
Expr::Or(Box::new((current_lhs, rhs, pos)))
}
Token::And => {
let rhs = args.pop();
let current_lhs = args.pop();
Expr::And(Box::new((current_lhs, rhs, pos)))
}
Token::In => {
let rhs = args.pop();
let current_lhs = args.pop();
make_in_expr(current_lhs, rhs, pos)?
}
#[cfg(not(feature = "no_object"))]
Token::Period => {
let rhs = args.pop();
let current_lhs = args.pop();
make_dot_expr(current_lhs, rhs, pos)?
}
Token::Custom(s)
if state
.engine
.custom_keywords
.as_ref()
.map(|c| c.contains_key(&s))
.unwrap_or(false) =>
{
// Accept non-native functions for custom operators
let op = (op.0, false, op.2);
Expr::FnCall(Box::new((op, None, hash, args, None)))
}
op_token => return Err(PERR::UnknownOperator(op_token.into()).into_err(pos)),
};
}
}
/// Parse an expression.
fn parse_expr(
input: &mut TokenStream,
state: &mut ParseState,
mut settings: ParseSettings,
) -> Result<Expr, ParseError> {
settings.pos = input.peek().unwrap().1;
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
let lhs = parse_unary(input, state, settings.level_up())?;
parse_binary_op(input, state, 1, lhs, settings.level_up())
}
/// Make sure that the expression is not a statement expression (i.e. wrapped in `{}`).
fn ensure_not_statement_expr(input: &mut TokenStream, type_name: &str) -> Result<(), ParseError> {
match input.peek().unwrap() {
// Disallow statement expressions
(Token::LeftBrace, pos) | (Token::EOF, pos) => {
Err(PERR::ExprExpected(type_name.to_string()).into_err(*pos))
}
// No need to check for others at this time - leave it for the expr parser
_ => Ok(()),
}
}
/// Make sure that the expression is not a mis-typed assignment (i.e. `a = b` instead of `a == b`).
fn ensure_not_assignment(input: &mut TokenStream) -> Result<(), ParseError> {
match input.peek().unwrap() {
(Token::Equals, pos) => {
return Err(PERR::BadInput("Possibly a typo of '=='?".to_string()).into_err(*pos))
}
(Token::PlusAssign, pos)
| (Token::MinusAssign, pos)
| (Token::MultiplyAssign, pos)
| (Token::DivideAssign, pos)
| (Token::LeftShiftAssign, pos)
| (Token::RightShiftAssign, pos)
| (Token::ModuloAssign, pos)
| (Token::PowerOfAssign, pos)
| (Token::AndAssign, pos)
| (Token::OrAssign, pos)
| (Token::XOrAssign, pos) => {
return Err(PERR::BadInput(
"Expecting a boolean expression, not an assignment".to_string(),
)
.into_err(*pos))
}
_ => Ok(()),
}
}
/// Parse an if statement.
fn parse_if(
input: &mut TokenStream,
state: &mut ParseState,
mut settings: ParseSettings,
) -> Result<Stmt, ParseError> {
// if ...
settings.pos = eat_token(input, Token::If);
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
// if guard { if_body }
ensure_not_statement_expr(input, "a boolean")?;
let guard = parse_expr(input, state, settings.level_up())?;
ensure_not_assignment(input)?;
let if_body = parse_block(input, state, settings.level_up())?;
// if guard { if_body } else ...
let else_body = if match_token(input, Token::Else).unwrap_or(false) {
Some(if let (Token::If, _) = input.peek().unwrap() {
// if guard { if_body } else if ...
parse_if(input, state, settings.level_up())?
} else {
// if guard { if_body } else { else-body }
parse_block(input, state, settings.level_up())?
})
} else {
None
};
Ok(Stmt::IfThenElse(Box::new((guard, if_body, else_body))))
}
/// Parse a while loop.
fn parse_while(
input: &mut TokenStream,
state: &mut ParseState,
mut settings: ParseSettings,
) -> Result<Stmt, ParseError> {
// while ...
settings.pos = eat_token(input, Token::While);
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
// while guard { body }
ensure_not_statement_expr(input, "a boolean")?;
let guard = parse_expr(input, state, settings.level_up())?;
ensure_not_assignment(input)?;
settings.is_breakable = true;
let body = parse_block(input, state, settings.level_up())?;
Ok(Stmt::While(Box::new((guard, body))))
}
/// Parse a loop statement.
fn parse_loop(
input: &mut TokenStream,
state: &mut ParseState,
mut settings: ParseSettings,
) -> Result<Stmt, ParseError> {
// loop ...
settings.pos = eat_token(input, Token::Loop);
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
// loop { body }
settings.is_breakable = true;
let body = parse_block(input, state, settings.level_up())?;
Ok(Stmt::Loop(Box::new(body)))
}
/// Parse a for loop.
fn parse_for(
input: &mut TokenStream,
state: &mut ParseState,
mut settings: ParseSettings,
) -> Result<Stmt, ParseError> {
// for ...
settings.pos = eat_token(input, Token::For);
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
// for name ...
let name = match input.next().unwrap() {
// Variable name
(Token::Identifier(s), _) => s,
// Bad identifier
(Token::LexError(err), pos) => return Err(err.into_err(pos)),
// EOF
(Token::EOF, pos) => return Err(PERR::VariableExpected.into_err(pos)),
// Not a variable name
(_, pos) => return Err(PERR::VariableExpected.into_err(pos)),
};
// for name in ...
match input.next().unwrap() {
(Token::In, _) => (),
(Token::LexError(err), pos) => return Err(err.into_err(pos)),
(_, pos) => {
return Err(
PERR::MissingToken(Token::In.into(), "after the iteration variable".into())
.into_err(pos),
)
}
}
// for name in expr { body }
ensure_not_statement_expr(input, "a boolean")?;
let expr = parse_expr(input, state, settings.level_up())?;
let prev_stack_len = state.stack.len();
state.stack.push((name.clone(), ScopeEntryType::Normal));
settings.is_breakable = true;
let body = parse_block(input, state, settings.level_up())?;
state.stack.truncate(prev_stack_len);
Ok(Stmt::For(Box::new((name, expr, body))))
}
/// Parse a variable definition statement.
fn parse_let(
input: &mut TokenStream,
state: &mut ParseState,
var_type: ScopeEntryType,
mut settings: ParseSettings,
) -> Result<Stmt, ParseError> {
// let/const... (specified in `var_type`)
settings.pos = input.next().unwrap().1;
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
// let name ...
let (name, pos) = match input.next().unwrap() {
(Token::Identifier(s), pos) => (s, pos),
(Token::LexError(err), pos) => return Err(err.into_err(pos)),
(_, pos) => return Err(PERR::VariableExpected.into_err(pos)),
};
// Check if the name is allowed
match name.as_str() {
KEYWORD_THIS => {
return Err(
PERR::BadInput(LexError::MalformedIdentifier(name).to_string()).into_err(pos),
)
}
_ => (),
}
// let name = ...
if match_token(input, Token::Equals)? {
// let name = expr
let init_value = parse_expr(input, state, settings.level_up())?;
match var_type {
// let name = expr
ScopeEntryType::Normal => {
state.stack.push((name.clone(), ScopeEntryType::Normal));
Ok(Stmt::Let(Box::new(((name, pos), Some(init_value)))))
}
// const name = { expr:constant }
ScopeEntryType::Constant if init_value.is_constant() => {
state.stack.push((name.clone(), ScopeEntryType::Constant));
Ok(Stmt::Const(Box::new(((name, pos), init_value))))
}
// const name = expr: error
ScopeEntryType::Constant => {
Err(PERR::ForbiddenConstantExpr(name).into_err(init_value.position()))
}
}
} else {
// let name
match var_type {
ScopeEntryType::Normal => {
state.stack.push((name.clone(), ScopeEntryType::Normal));
Ok(Stmt::Let(Box::new(((name, pos), None))))
}
ScopeEntryType::Constant => {
state.stack.push((name.clone(), ScopeEntryType::Constant));
Ok(Stmt::Const(Box::new(((name, pos), Expr::Unit(pos)))))
}
}
}
}
/// Parse an import statement.
#[cfg(not(feature = "no_module"))]
fn parse_import(
input: &mut TokenStream,
state: &mut ParseState,
mut settings: ParseSettings,
) -> Result<Stmt, ParseError> {
// import ...
settings.pos = eat_token(input, Token::Import);
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
// import expr ...
let expr = parse_expr(input, state, settings.level_up())?;
// import expr as ...
match input.next().unwrap() {
(Token::As, _) => (),
(_, pos) => {
return Err(
PERR::MissingToken(Token::As.into(), "in this import statement".into())
.into_err(pos),
)
}
}
// import expr as name ...
let (name, _) = match input.next().unwrap() {
(Token::Identifier(s), pos) => (s, pos),
(Token::LexError(err), pos) => return Err(err.into_err(pos)),
(_, pos) => return Err(PERR::VariableExpected.into_err(pos)),
};
state.modules.push(name.clone());
Ok(Stmt::Import(Box::new((expr, (name, settings.pos)))))
}
/// Parse an export statement.
#[cfg(not(feature = "no_module"))]
fn parse_export(
input: &mut TokenStream,
state: &mut ParseState,
mut settings: ParseSettings,
) -> Result<Stmt, ParseError> {
settings.pos = eat_token(input, Token::Export);
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
let mut exports = StaticVec::new();
loop {
let (id, id_pos) = match input.next().unwrap() {
(Token::Identifier(s), pos) => (s.clone(), pos),
(Token::LexError(err), pos) => return Err(err.into_err(pos)),
(_, pos) => return Err(PERR::VariableExpected.into_err(pos)),
};
let rename = if match_token(input, Token::As)? {
match input.next().unwrap() {
(Token::Identifier(s), pos) => Some((s.clone(), pos)),
(_, pos) => return Err(PERR::VariableExpected.into_err(pos)),
}
} else {
None
};
exports.push(((id, id_pos), rename));
match input.peek().unwrap() {
(Token::Comma, _) => {
eat_token(input, Token::Comma);
}
(Token::Identifier(_), pos) => {
return Err(PERR::MissingToken(
Token::Comma.into(),
"to separate the list of exports".into(),
)
.into_err(*pos))
}
_ => break,
}
}
// Check for duplicating parameters
exports
.iter()
.enumerate()
.try_for_each(|(i, ((id1, _), _))| {
exports
.iter()
.skip(i + 1)
.find(|((id2, _), _)| id2 == id1)
.map_or_else(|| Ok(()), |((id2, pos), _)| Err((id2, *pos)))
})
.map_err(|(id2, pos)| PERR::DuplicatedExport(id2.to_string()).into_err(pos))?;
Ok(Stmt::Export(Box::new(exports)))
}
/// Parse a statement block.
fn parse_block(
input: &mut TokenStream,
state: &mut ParseState,
mut settings: ParseSettings,
) -> Result<Stmt, ParseError> {
// Must start with {
settings.pos = match input.next().unwrap() {
(Token::LeftBrace, pos) => pos,
(Token::LexError(err), pos) => return Err(err.into_err(pos)),
(_, pos) => {
return Err(PERR::MissingToken(
Token::LeftBrace.into(),
"to start a statement block".into(),
)
.into_err(pos))
}
};
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
let mut statements = StaticVec::new();
let prev_stack_len = state.stack.len();
let prev_mods_len = state.modules.len();
while !match_token(input, Token::RightBrace)? {
// Parse statements inside the block
settings.is_global = false;
let stmt = parse_stmt(input, state, settings.level_up())?;
// See if it needs a terminating semicolon
let need_semicolon = !stmt.is_self_terminated();
statements.push(stmt);
match input.peek().unwrap() {
// { ... stmt }
(Token::RightBrace, _) => {
eat_token(input, Token::RightBrace);
break;
}
// { ... stmt;
(Token::SemiColon, _) if need_semicolon => {
eat_token(input, Token::SemiColon);
}
// { ... { stmt } ;
(Token::SemiColon, _) if !need_semicolon => (),
// { ... { stmt } ???
(_, _) if !need_semicolon => (),
// { ... stmt <error>
(Token::LexError(err), pos) => return Err(err.into_err(*pos)),
// { ... stmt ???
(_, pos) => {
// Semicolons are not optional between statements
return Err(PERR::MissingToken(
Token::SemiColon.into(),
"to terminate this statement".into(),
)
.into_err(*pos));
}
}
}
state.stack.truncate(prev_stack_len);
state.modules.truncate(prev_mods_len);
Ok(Stmt::Block(Box::new((statements, settings.pos))))
}
/// Parse an expression as a statement.
fn parse_expr_stmt(
input: &mut TokenStream,
state: &mut ParseState,
mut settings: ParseSettings,
) -> Result<Stmt, ParseError> {
settings.pos = input.peek().unwrap().1;
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
let expr = parse_expr(input, state, settings.level_up())?;
let expr = parse_op_assignment_stmt(input, state, expr, settings.level_up())?;
Ok(Stmt::Expr(Box::new(expr)))
}
/// Parse a single statement.
fn parse_stmt(
input: &mut TokenStream,
state: &mut ParseState,
mut settings: ParseSettings,
) -> Result<Stmt, ParseError> {
use ScopeEntryType::{Constant, Normal};
let (token, token_pos) = match input.peek().unwrap() {
(Token::EOF, pos) => return Ok(Stmt::Noop(*pos)),
x => x,
};
settings.pos = *token_pos;
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
match token {
// Semicolon - empty statement
Token::SemiColon => Ok(Stmt::Noop(settings.pos)),
Token::LeftBrace => parse_block(input, state, settings.level_up()),
// fn ...
#[cfg(not(feature = "no_function"))]
Token::Fn if !settings.is_global => Err(PERR::WrongFnDefinition.into_err(settings.pos)),
#[cfg(not(feature = "no_function"))]
Token::Fn => unreachable!(),
Token::If => parse_if(input, state, settings.level_up()),
Token::While => parse_while(input, state, settings.level_up()),
Token::Loop => parse_loop(input, state, settings.level_up()),
Token::For => parse_for(input, state, settings.level_up()),
Token::Continue if settings.is_breakable => {
let pos = eat_token(input, Token::Continue);
Ok(Stmt::Continue(pos))
}
Token::Break if settings.is_breakable => {
let pos = eat_token(input, Token::Break);
Ok(Stmt::Break(pos))
}
Token::Continue | Token::Break => Err(PERR::LoopBreak.into_err(settings.pos)),
Token::Return | Token::Throw => {
let return_type = match input.next().unwrap() {
(Token::Return, _) => ReturnType::Return,
(Token::Throw, _) => ReturnType::Exception,
_ => unreachable!(),
};
match input.peek().unwrap() {
// `return`/`throw` at <EOF>
(Token::EOF, pos) => Ok(Stmt::ReturnWithVal(Box::new(((return_type, *pos), None)))),
// `return;` or `throw;`
(Token::SemiColon, _) => Ok(Stmt::ReturnWithVal(Box::new((
(return_type, settings.pos),
None,
)))),
// `return` or `throw` with expression
(_, _) => {
let expr = parse_expr(input, state, settings.level_up())?;
let pos = expr.position();
Ok(Stmt::ReturnWithVal(Box::new((
(return_type, pos),
Some(expr),
))))
}
}
}
Token::Let => parse_let(input, state, Normal, settings.level_up()),
Token::Const => parse_let(input, state, Constant, settings.level_up()),
#[cfg(not(feature = "no_module"))]
Token::Import => parse_import(input, state, settings.level_up()),
#[cfg(not(feature = "no_module"))]
Token::Export if !settings.is_global => Err(PERR::WrongExport.into_err(settings.pos)),
#[cfg(not(feature = "no_module"))]
Token::Export => parse_export(input, state, settings.level_up()),
_ => parse_expr_stmt(input, state, settings.level_up()),
}
}
/// Parse a function definition.
#[cfg(not(feature = "no_function"))]
fn parse_fn(
input: &mut TokenStream,
state: &mut ParseState,
access: FnAccess,
mut settings: ParseSettings,
) -> Result<ScriptFnDef, ParseError> {
settings.pos = eat_token(input, Token::Fn);
settings.ensure_level_within_max_limit(state.max_expr_depth)?;
let name = match input.next().unwrap() {
(Token::Identifier(s), _) | (Token::Custom(s), _) => s,
(_, pos) => return Err(PERR::FnMissingName.into_err(pos)),
};
match input.peek().unwrap() {
(Token::LeftParen, _) => eat_token(input, Token::LeftParen),
(_, pos) => return Err(PERR::FnMissingParams(name).into_err(*pos)),
};
let mut params = Vec::new();
if !match_token(input, Token::RightParen)? {
let end_err = format!("to close the parameters list of function '{}'", name);
let sep_err = format!("to separate the parameters of function '{}'", name);
loop {
match input.peek().unwrap() {
(Token::RightParen, _) => (),
_ => match input.next().unwrap() {
(Token::Identifier(s), pos) => {
state.stack.push((s.clone(), ScopeEntryType::Normal));
params.push((s, pos))
}
(Token::LexError(err), pos) => return Err(err.into_err(pos)),
(_, pos) => {
return Err(
PERR::MissingToken(Token::RightParen.into(), end_err).into_err(pos)
)
}
},
}
match input.next().unwrap() {
(Token::RightParen, _) => break,
(Token::Comma, _) => (),
(Token::Identifier(_), pos) => {
return Err(PERR::MissingToken(Token::Comma.into(), sep_err).into_err(pos))
}
(Token::LexError(err), pos) => return Err(err.into_err(pos)),
(_, pos) => {
return Err(PERR::MissingToken(Token::Comma.into(), sep_err).into_err(pos))
}
}
}
}
// Check for duplicating parameters
params
.iter()
.enumerate()
.try_for_each(|(i, (p1, _))| {
params
.iter()
.skip(i + 1)
.find(|(p2, _)| p2 == p1)
.map_or_else(|| Ok(()), |(p2, pos)| Err((p2, *pos)))
})
.map_err(|(p, pos)| {
PERR::FnDuplicatedParam(name.to_string(), p.to_string()).into_err(pos)
})?;
// Parse function body
let body = match input.peek().unwrap() {
(Token::LeftBrace, _) => {
settings.is_breakable = false;
parse_block(input, state, settings.level_up())?
}
(_, pos) => return Err(PERR::FnMissingBody(name).into_err(*pos)),
};
let params = params.into_iter().map(|(p, _)| p).collect();
Ok(ScriptFnDef {
name,
access,
params,
body,
pos: settings.pos,
})
}
impl Engine {
pub(crate) fn parse_global_expr(
&self,
input: &mut TokenStream,
scope: &Scope,
optimization_level: OptimizationLevel,
) -> Result<AST, ParseError> {
let mut state = ParseState::new(self, self.max_expr_depth);
let settings = ParseSettings {
allow_if_expr: false,
allow_stmt_expr: false,
is_global: true,
is_breakable: false,
level: 0,
pos: Position::none(),
};
let expr = parse_expr(input, &mut state, settings)?;
match input.peek().unwrap() {
(Token::EOF, _) => (),
// Return error if the expression doesn't end
(token, pos) => {
return Err(
PERR::BadInput(format!("Unexpected '{}'", token.syntax())).into_err(*pos)
)
}
}
let expr = vec![Stmt::Expr(Box::new(expr))];
Ok(
// Optimize AST
optimize_into_ast(self, scope, expr, Default::default(), optimization_level),
)
}
/// Parse the global level statements.
fn parse_global_level(
&self,
input: &mut TokenStream,
) -> Result<(Vec<Stmt>, Vec<ScriptFnDef>), ParseError> {
let mut statements = Vec::<Stmt>::new();
let mut functions = HashMap::<u64, ScriptFnDef, _>::with_hasher(StraightHasherBuilder);
let mut state = ParseState::new(self, self.max_expr_depth);
while !input.peek().unwrap().0.is_eof() {
// Collect all the function definitions
#[cfg(not(feature = "no_function"))]
{
let (access, must_be_fn) = if match_token(input, Token::Private)? {
(FnAccess::Private, true)
} else {
(FnAccess::Public, false)
};
match input.peek().unwrap() {
(Token::Fn, pos) => {
let mut state = ParseState::new(self, self.max_function_expr_depth);
let settings = ParseSettings {
allow_if_expr: true,
allow_stmt_expr: true,
is_global: false,
is_breakable: false,
level: 0,
pos: *pos,
};
let func = parse_fn(input, &mut state, access, settings)?;
// Qualifiers (none) + function name + number of arguments.
let hash = calc_fn_hash(empty(), &func.name, func.params.len(), empty());
functions.insert(hash, func);
continue;
}
(_, pos) if must_be_fn => {
return Err(PERR::MissingToken(
Token::Fn.into(),
format!("following '{}'", Token::Private.syntax()),
)
.into_err(*pos))
}
_ => (),
}
}
// Actual statement
let settings = ParseSettings {
allow_if_expr: true,
allow_stmt_expr: true,
is_global: true,
is_breakable: false,
level: 0,
pos: Position::none(),
};
let stmt = parse_stmt(input, &mut state, settings)?;
let need_semicolon = !stmt.is_self_terminated();
statements.push(stmt);
match input.peek().unwrap() {
// EOF
(Token::EOF, _) => break,
// stmt ;
(Token::SemiColon, _) if need_semicolon => {
eat_token(input, Token::SemiColon);
}
// stmt ;
(Token::SemiColon, _) if !need_semicolon => (),
// { stmt } ???
(_, _) if !need_semicolon => (),
// stmt <error>
(Token::LexError(err), pos) => return Err(err.into_err(*pos)),
// stmt ???
(_, pos) => {
// Semicolons are not optional between statements
return Err(PERR::MissingToken(
Token::SemiColon.into(),
"to terminate this statement".into(),
)
.into_err(*pos));
}
}
}
Ok((statements, functions.into_iter().map(|(_, v)| v).collect()))
}
/// Run the parser on an input stream, returning an AST.
pub(crate) fn parse(
&self,
input: &mut TokenStream,
scope: &Scope,
optimization_level: OptimizationLevel,
) -> Result<AST, ParseError> {
let (statements, lib) = self.parse_global_level(input)?;
Ok(
// Optimize AST
optimize_into_ast(self, scope, statements, lib, optimization_level),
)
}
}
/// Map a `Dynamic` value to an expression.
///
/// Returns Some(expression) if conversion is successful. Otherwise None.
pub fn map_dynamic_to_expr(value: Dynamic, pos: Position) -> Option<Expr> {
match value.0 {
#[cfg(not(feature = "no_float"))]
Union::Float(value) => Some(Expr::FloatConstant(Box::new((value, pos)))),
Union::Unit(_) => Some(Expr::Unit(pos)),
Union::Int(value) => Some(Expr::IntegerConstant(Box::new((value, pos)))),
Union::Char(value) => Some(Expr::CharConstant(Box::new((value, pos)))),
Union::Str(value) => Some(Expr::StringConstant(Box::new((value.clone(), pos)))),
Union::Bool(true) => Some(Expr::True(pos)),
Union::Bool(false) => Some(Expr::False(pos)),
#[cfg(not(feature = "no_index"))]
Union::Array(array) => {
let items: Vec<_> = array
.into_iter()
.map(|x| map_dynamic_to_expr(x, pos))
.collect();
if items.iter().all(Option::is_some) {
Some(Expr::Array(Box::new((
items.into_iter().map(Option::unwrap).collect(),
pos,
))))
} else {
None
}
}
#[cfg(not(feature = "no_object"))]
Union::Map(map) => {
let items: Vec<_> = map
.into_iter()
.map(|(k, v)| ((k, pos), map_dynamic_to_expr(v, pos)))
.collect();
if items.iter().all(|(_, expr)| expr.is_some()) {
Some(Expr::Map(Box::new((
items
.into_iter()
.map(|((k, pos), expr)| ((k, pos), expr.unwrap()))
.collect(),
pos,
))))
} else {
None
}
}
_ => None,
}
}
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