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bc0d43d68f
rhai/src/parser.rs
Stephen Chung bc0d43d68f Simplify code.
2020-04-11 18:09:03 +08:00

2912 lines
95 KiB
Rust
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//! Main module defining the lexer and parser.
use crate::any::{Any, AnyExt, Dynamic};
use crate::engine::{Array, Engine, FunctionsLib, Map};
use crate::error::{LexError, ParseError, ParseErrorType};
use crate::optimize::{optimize_into_ast, OptimizationLevel};
use crate::scope::{EntryType as ScopeEntryType, Scope};
use crate::stdlib::{
borrow::Cow,
boxed::Box,
char,
collections::HashMap,
fmt,
fmt::Display,
format,
iter::Peekable,
ops::Add,
rc::Rc,
str::Chars,
str::FromStr,
string::{String, ToString},
sync::Arc,
usize, 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.
pub type FLOAT = f64;
type LERR = LexError;
type PERR = ParseErrorType;
/// A location (line number + character position) in the input script.
#[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Clone, Copy)]
pub struct Position {
/// Line number - 0 = none, MAX = EOF
line: usize,
/// Character position - 0 = BOL, MAX = EOF
pos: usize,
}
impl Position {
/// Create a new `Position`.
pub fn new(line: usize, position: usize) -> Self {
assert!(line != 0, "line cannot be zero");
assert!(
line != usize::MAX || position != usize::MAX,
"invalid position"
);
Self {
line,
pos: position,
}
}
/// Get the line number (1-based), or `None` if no position or EOF.
pub fn line(&self) -> Option<usize> {
if self.is_none() || self.is_eof() {
None
} else {
Some(self.line)
}
}
/// Get the character position (1-based), or `None` if at beginning of a line.
pub fn position(&self) -> Option<usize> {
if self.is_none() || self.is_eof() || self.pos == 0 {
None
} else {
Some(self.pos)
}
}
/// Advance by one character position.
pub(crate) fn advance(&mut self) {
self.pos += 1;
}
/// Go backwards by one character position.
///
/// # Panics
///
/// Panics if already at beginning of a line - cannot rewind to a previous line.
///
pub(crate) fn rewind(&mut self) {
assert!(self.pos > 0, "cannot rewind at position 0");
self.pos -= 1;
}
/// Advance to the next line.
pub(crate) fn new_line(&mut self) {
self.line += 1;
self.pos = 0;
}
/// Create a `Position` representing no position.
pub(crate) fn none() -> Self {
Self { line: 0, pos: 0 }
}
/// Create a `Position` at EOF.
pub(crate) fn eof() -> Self {
Self {
line: usize::MAX,
pos: usize::MAX,
}
}
/// Is there no `Position`?
pub fn is_none(&self) -> bool {
self.line == 0 && self.pos == 0
}
/// Is the `Position` at EOF?
pub fn is_eof(&self) -> bool {
self.line == usize::MAX && self.pos == usize::MAX
}
}
impl Default for Position {
fn default() -> Self {
Self::new(1, 0)
}
}
impl fmt::Display for Position {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if self.is_eof() {
write!(f, "EOF")
} else if self.is_none() {
write!(f, "none")
} else {
write!(f, "line {}, position {}", self.line, self.pos)
}
}
}
impl fmt::Debug for Position {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if self.is_eof() {
write!(f, "(EOF)")
} else {
write!(f, "({}:{})", self.line, self.pos)
}
}
}
/// 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)]
pub struct AST(
pub(crate) Vec<Stmt>,
#[cfg(feature = "sync")] pub(crate) Arc<FunctionsLib>,
#[cfg(not(feature = "sync"))] pub(crate) Rc<FunctionsLib>,
);
impl AST {
/// Create a new `AST`.
pub fn new() -> Self {
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<(), 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 {
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![],
};
#[cfg(feature = "sync")]
{
Self(ast, Arc::new(functions.merge(other.1.as_ref())))
}
#[cfg(not(feature = "sync"))]
{
Self(ast, Rc::new(functions.merge(other.1.as_ref())))
}
}
/// Clear all function definitions in the `AST`.
pub fn clear_functions(&mut self) {
#[cfg(feature = "sync")]
{
self.1 = Arc::new(FunctionsLib::new());
}
#[cfg(not(feature = "sync"))]
{
self.1 = Rc::new(FunctionsLib::new());
}
}
/// Clear all statements in the `AST`, leaving only function definitions.
pub fn retain_functions(&mut self) {
self.0 = vec![];
}
}
impl Default for AST {
fn default() -> Self {
#[cfg(feature = "sync")]
{
Self(vec![], Arc::new(FunctionsLib::new()))
}
#[cfg(not(feature = "sync"))]
{
Self(vec![], Rc::new(FunctionsLib::new()))
}
}
}
impl Add<Self> for &AST {
type Output = AST;
fn add(self, rhs: Self) -> Self::Output {
self.merge(rhs)
}
}
/// A script-function definition.
#[derive(Debug, Clone)]
pub struct FnDef {
/// Function name.
pub name: String,
/// Names of function parameters.
pub params: Vec<String>,
/// Function body.
pub body: Stmt,
/// Position of the function definition.
pub pos: Position,
}
/// `return`/`throw` statement.
#[derive(Debug, PartialEq, Eq, Hash, Clone, Copy)]
pub enum ReturnType {
/// `return` statement.
Return,
/// `throw` statement.
Exception,
}
/// A statement.
#[derive(Debug, Clone)]
pub enum Stmt {
/// No-op.
Noop(Position),
/// if expr { stmt } else { stmt }
IfThenElse(Box<Expr>, Box<Stmt>, Option<Box<Stmt>>),
/// while expr { stmt }
While(Box<Expr>, Box<Stmt>),
/// loop { stmt }
Loop(Box<Stmt>),
/// for id in expr { stmt }
For(Cow<'static, str>, Box<Expr>, Box<Stmt>),
/// let id = expr
Let(Cow<'static, str>, Option<Box<Expr>>, Position),
/// const id = expr
Const(Cow<'static, str>, Box<Expr>, Position),
/// { stmt; ... }
Block(Vec<Stmt>, Position),
/// { stmt }
Expr(Box<Expr>),
/// continue
Continue(Position),
/// break
Break(Position),
/// `return`/`throw`
ReturnWithVal(Option<Box<Expr>>, ReturnType, Position),
}
impl Stmt {
/// Get the `Position` of this statement.
pub fn position(&self) -> Position {
match self {
Stmt::Noop(pos)
| Stmt::Let(_, _, pos)
| Stmt::Const(_, _, pos)
| Stmt::Block(_, pos)
| Stmt::Continue(pos)
| Stmt::Break(pos)
| Stmt::ReturnWithVal(_, _, pos) => *pos,
Stmt::IfThenElse(expr, _, _) | Stmt::Expr(expr) => expr.position(),
Stmt::While(_, stmt) | Stmt::Loop(stmt) | Stmt::For(_, _, stmt) => stmt.position(),
}
}
/// 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::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(guard, if_block, Some(else_block)) => {
guard.is_pure() && if_block.is_pure() && else_block.is_pure()
}
Stmt::IfThenElse(guard, block, None) | Stmt::While(guard, block) => {
guard.is_pure() && block.is_pure()
}
Stmt::Loop(block) => block.is_pure(),
Stmt::For(_, range, block) => range.is_pure() && block.is_pure(),
Stmt::Let(_, _, _) | Stmt::Const(_, _, _) => false,
Stmt::Block(statements, _) => statements.iter().all(Stmt::is_pure),
Stmt::Continue(_) | Stmt::Break(_) | Stmt::ReturnWithVal(_, _, _) => false,
}
}
}
/// An expression.
#[derive(Debug, Clone)]
pub enum Expr {
/// Integer constant.
IntegerConstant(INT, Position),
/// Floating-point constant.
FloatConstant(FLOAT, Position),
/// Character constant.
CharConstant(char, Position),
/// String constant.
StringConstant(Cow<'static, str>, Position),
/// Variable access.
Variable(Cow<'static, str>, Position),
/// Property access.
Property(Cow<'static, str>, Position),
/// { stmt }
Stmt(Box<Stmt>, Position),
/// func(expr, ... )
FunctionCall(Cow<'static, str>, Vec<Expr>, Option<Dynamic>, Position),
/// expr = expr
Assignment(Box<Expr>, Box<Expr>, Position),
/// lhs.rhs
Dot(Box<Expr>, Box<Expr>, Position),
/// expr[expr]
Index(Box<Expr>, Box<Expr>, Position),
/// [ expr, ... ]
Array(Vec<Expr>, Position),
/// #{ name:expr, ... }
Map(Vec<(String, Expr, Position)>, Position),
/// lhs in rhs
In(Box<Expr>, Box<Expr>, Position),
/// lhs && rhs
And(Box<Expr>, Box<Expr>, Position),
/// lhs || rhs
Or(Box<Expr>, Box<Expr>, Position),
/// true
True(Position),
/// false
False(Position),
/// ()
Unit(Position),
}
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::IntegerConstant(i, _) => i.into_dynamic(),
Self::FloatConstant(f, _) => f.into_dynamic(),
Self::CharConstant(c, _) => c.into_dynamic(),
Self::StringConstant(s, _) => s.clone().into_owned().into_dynamic(),
Self::True(_) => true.into_dynamic(),
Self::False(_) => false.into_dynamic(),
Self::Unit(_) => ().into_dynamic(),
Self::Array(items, _) if items.iter().all(Self::is_constant) => items
.iter()
.map(Self::get_constant_value)
.collect::<Vec<_>>()
.into_dynamic(),
Self::Map(items, _) if items.iter().all(|(_, v, _)| v.is_constant()) => items
.iter()
.map(|(k, v, _)| (k.clone(), v.get_constant_value()))
.collect::<HashMap<_, _>>()
.into_dynamic(),
_ => panic!("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::IntegerConstant(i, _) => i.to_string(),
Self::FloatConstant(f, _) => f.to_string(),
Self::CharConstant(c, _) => c.to_string(),
Self::StringConstant(_, _) => "string".to_string(),
Self::True(_) => "true".to_string(),
Self::False(_) => "false".to_string(),
Self::Unit(_) => "()".to_string(),
Self::Array(items, _) if items.iter().all(Self::is_constant) => "array".to_string(),
_ => panic!("cannot get value of non-constant expression"),
}
}
/// Get the `Position` of the expression.
pub fn position(&self) -> Position {
match self {
Self::IntegerConstant(_, pos)
| Self::FloatConstant(_, pos)
| Self::CharConstant(_, pos)
| Self::StringConstant(_, pos)
| Self::Array(_, pos)
| Self::Map(_, pos)
| Self::Variable(_, pos)
| Self::Property(_, pos)
| Self::Stmt(_, pos)
| Self::FunctionCall(_, _, _, pos)
| Self::And(_, _, pos)
| Self::Or(_, _, pos)
| Self::In(_, _, pos)
| Self::True(pos)
| Self::False(pos)
| Self::Unit(pos) => *pos,
Self::Assignment(expr, _, _) | Self::Dot(expr, _, _) | Self::Index(expr, _, _) => {
expr.position()
}
}
}
/// Get the `Position` of the expression.
pub(crate) fn set_position(mut self, new_pos: Position) -> Self {
match &mut self {
Self::IntegerConstant(_, pos)
| Self::FloatConstant(_, pos)
| Self::CharConstant(_, pos)
| Self::StringConstant(_, pos)
| Self::Array(_, pos)
| Self::Map(_, pos)
| Self::Variable(_, pos)
| Self::Property(_, pos)
| Self::Stmt(_, pos)
| Self::FunctionCall(_, _, _, pos)
| Self::And(_, _, pos)
| Self::Or(_, _, pos)
| Self::In(_, _, pos)
| Self::True(pos)
| Self::False(pos)
| Self::Unit(pos)
| Self::Assignment(_, _, pos)
| Self::Dot(_, _, pos)
| Self::Index(_, _, pos) => *pos = new_pos,
}
self
}
/// Is the expression pure?
///
/// A pure expression has no side effects.
pub fn is_pure(&self) -> bool {
match self {
Self::Array(expressions, _) => expressions.iter().all(Self::is_pure),
Self::Index(x, y, _) | Self::And(x, y, _) | Self::Or(x, y, _) | Self::In(x, y, _) => {
x.is_pure() && y.is_pure()
}
Self::Stmt(stmt, _) => stmt.is_pure(),
expr => expr.is_constant() || matches!(expr, Self::Variable(_, _)),
}
}
/// Is the expression a constant?
pub fn is_constant(&self) -> bool {
match self {
Self::IntegerConstant(_, _)
| Self::FloatConstant(_, _)
| Self::CharConstant(_, _)
| Self::StringConstant(_, _)
| Self::True(_)
| Self::False(_)
| Self::Unit(_) => true,
// An array literal is constant if all items are constant
Self::Array(expressions, _) => expressions.iter().all(Self::is_constant),
// An map literal is constant if all items are constant
Self::Map(items, _) => items.iter().map(|(_, expr, _)| expr).all(Self::is_constant),
// Check in expression
Self::In(lhs, rhs, _) => match (lhs.as_ref(), rhs.as_ref()) {
(Self::StringConstant(_, _), Self::StringConstant(_, _))
| (Self::CharConstant(_, _), Self::StringConstant(_, _)) => true,
_ => false,
},
_ => false,
}
}
}
/// Tokens.
#[derive(Debug, PartialEq, Clone)]
pub enum Token {
IntegerConstant(INT),
FloatConstant(FLOAT),
Identifier(String),
CharConstant(char),
StringConst(String),
LeftBrace,
RightBrace,
LeftParen,
RightParen,
LeftBracket,
RightBracket,
Plus,
UnaryPlus,
Minus,
UnaryMinus,
Multiply,
Divide,
Modulo,
PowerOf,
LeftShift,
RightShift,
SemiColon,
Colon,
Comma,
Period,
#[cfg(not(feature = "no_object"))]
MapStart,
Equals,
True,
False,
Let,
Const,
If,
Else,
While,
Loop,
For,
In,
LessThan,
GreaterThan,
LessThanEqualsTo,
GreaterThanEqualsTo,
EqualsTo,
NotEqualsTo,
Bang,
Pipe,
Or,
XOr,
Ampersand,
And,
#[cfg(not(feature = "no_function"))]
Fn,
Continue,
Break,
Return,
Throw,
PlusAssign,
MinusAssign,
MultiplyAssign,
DivideAssign,
LeftShiftAssign,
RightShiftAssign,
AndAssign,
OrAssign,
XOrAssign,
ModuloAssign,
PowerOfAssign,
LexError(Box<LexError>),
}
impl Token {
/// Get the syntax of the token.
pub fn syntax(&self) -> Cow<str> {
use Token::*;
match self {
IntegerConstant(i) => i.to_string().into(),
FloatConstant(f) => f.to_string().into(),
Identifier(s) => s.into(),
CharConstant(c) => c.to_string().into(),
LexError(err) => err.to_string().into(),
token => (match token {
StringConst(_) => "string",
LeftBrace => "{",
RightBrace => "}",
LeftParen => "(",
RightParen => ")",
LeftBracket => "[",
RightBracket => "]",
Plus => "+",
UnaryPlus => "+",
Minus => "-",
UnaryMinus => "-",
Multiply => "*",
Divide => "/",
SemiColon => ";",
Colon => ":",
Comma => ",",
Period => ".",
#[cfg(not(feature = "no_object"))]
MapStart => "#{",
Equals => "=",
True => "true",
False => "false",
Let => "let",
Const => "const",
If => "if",
Else => "else",
While => "while",
Loop => "loop",
LessThan => "<",
GreaterThan => ">",
Bang => "!",
LessThanEqualsTo => "<=",
GreaterThanEqualsTo => ">=",
EqualsTo => "==",
NotEqualsTo => "!=",
Pipe => "|",
Or => "||",
Ampersand => "&",
And => "&&",
#[cfg(not(feature = "no_function"))]
Fn => "fn",
Continue => "continue",
Break => "break",
Return => "return",
Throw => "throw",
PlusAssign => "+=",
MinusAssign => "-=",
MultiplyAssign => "*=",
DivideAssign => "/=",
LeftShiftAssign => "<<=",
RightShiftAssign => ">>=",
AndAssign => "&=",
OrAssign => "|=",
XOrAssign => "^=",
LeftShift => "<<",
RightShift => ">>",
XOr => "^",
Modulo => "%",
ModuloAssign => "%=",
PowerOf => "~",
PowerOfAssign => "~=",
For => "for",
In => "in",
_ => panic!("operator should be match in outer scope"),
})
.into(),
}
}
// If another operator is after these, it's probably an unary operator
// (not sure about fn name).
pub fn is_next_unary(&self) -> bool {
use Token::*;
match self {
LexError(_) |
LeftBrace | // (+expr) - is unary
// RightBrace | {expr} - expr not unary & is closing
LeftParen | // {-expr} - is unary
// RightParen | (expr) - expr not unary & is closing
LeftBracket | // [-expr] - is unary
// RightBracket | [expr] - expr not unary & is closing
Plus |
UnaryPlus |
Minus |
UnaryMinus |
Multiply |
Divide |
Colon |
Comma |
Period |
Equals |
LessThan |
GreaterThan |
Bang |
LessThanEqualsTo |
GreaterThanEqualsTo |
EqualsTo |
NotEqualsTo |
Pipe |
Or |
Ampersand |
And |
If |
While |
PlusAssign |
MinusAssign |
MultiplyAssign |
DivideAssign |
LeftShiftAssign |
RightShiftAssign |
AndAssign |
OrAssign |
XOrAssign |
LeftShift |
RightShift |
XOr |
Modulo |
ModuloAssign |
Return |
Throw |
PowerOf |
In |
PowerOfAssign => true,
_ => false,
}
}
/// Get the precedence number of the token.
pub fn precedence(&self) -> u8 {
use Token::*;
match self {
Equals | PlusAssign | MinusAssign | MultiplyAssign | DivideAssign | LeftShiftAssign
| RightShiftAssign | AndAssign | OrAssign | XOrAssign | ModuloAssign
| PowerOfAssign => 10,
Or | XOr | Pipe => 40,
And | Ampersand => 50,
LessThan | LessThanEqualsTo | GreaterThan | GreaterThanEqualsTo | EqualsTo
| NotEqualsTo => 60,
In => 70,
Plus | Minus => 80,
Divide | Multiply | PowerOf => 90,
LeftShift | RightShift => 100,
Modulo => 110,
Period => 120,
_ => 0,
}
}
/// Does an expression bind to the right (instead of left)?
pub fn is_bind_right(&self) -> bool {
use Token::*;
match self {
// Assignments bind to the right
Equals | PlusAssign | MinusAssign | MultiplyAssign | DivideAssign | LeftShiftAssign
| RightShiftAssign | AndAssign | OrAssign | XOrAssign | ModuloAssign
| PowerOfAssign => true,
// Property access binds to the right
Period => true,
_ => false,
}
}
}
/// An iterator on a `Token` stream.
pub struct TokenIterator<'a> {
/// Can the next token be a unary operator?
can_be_unary: bool,
/// Current position.
pos: Position,
/// The input character streams.
streams: Vec<Peekable<Chars<'a>>>,
}
impl<'a> TokenIterator<'a> {
/// Consume the next character.
fn eat_next(&mut self) {
self.get_next();
self.advance();
}
/// Get the next character
fn get_next(&mut self) -> Option<char> {
loop {
if self.streams.is_empty() {
return None;
} else if let Some(ch) = self.streams[0].next() {
return Some(ch);
} else {
let _ = self.streams.remove(0);
}
}
}
/// Peek the next character
fn peek_next(&mut self) -> Option<char> {
loop {
if self.streams.is_empty() {
return None;
} else if let Some(ch) = self.streams[0].peek() {
return Some(*ch);
} else {
let _ = self.streams.remove(0);
}
}
}
/// Move the current position one character ahead.
fn advance(&mut self) {
self.pos.advance();
}
/// Move the current position back one character.
///
/// # Panics
///
/// Panics if already at the beginning of a line - cannot rewind to the previous line.
fn rewind(&mut self) {
self.pos.rewind();
}
/// Move the current position to the next line.
fn new_line(&mut self) {
self.pos.new_line()
}
/// Parse a string literal wrapped by `enclosing_char`.
pub fn parse_string_literal(
&mut self,
enclosing_char: char,
) -> Result<String, (LexError, Position)> {
let mut result = Vec::new();
let mut escape = String::with_capacity(12);
loop {
let next_char = self.get_next();
self.advance();
match next_char.ok_or((LERR::UnterminatedString, Position::eof()))? {
// \...
'\\' if escape.is_empty() => {
escape.push('\\');
}
// \\
'\\' if !escape.is_empty() => {
escape.clear();
result.push('\\');
}
// \t
't' if !escape.is_empty() => {
escape.clear();
result.push('\t');
}
// \n
'n' if !escape.is_empty() => {
escape.clear();
result.push('\n');
}
// \r
'r' if !escape.is_empty() => {
escape.clear();
result.push('\r');
}
// \x??, \u????, \U????????
ch @ 'x' | ch @ 'u' | ch @ 'U' if !escape.is_empty() => {
let mut seq = escape.clone();
seq.push(ch);
escape.clear();
let mut out_val: u32 = 0;
let len = match ch {
'x' => 2,
'u' => 4,
'U' => 8,
_ => panic!("should be 'x', 'u' or 'U'"),
};
for _ in 0..len {
let c = self.get_next().ok_or_else(|| {
(LERR::MalformedEscapeSequence(seq.to_string()), self.pos)
})?;
seq.push(c);
self.advance();
out_val *= 16;
out_val += c.to_digit(16).ok_or_else(|| {
(LERR::MalformedEscapeSequence(seq.to_string()), self.pos)
})?;
}
result.push(
char::from_u32(out_val)
.ok_or_else(|| (LERR::MalformedEscapeSequence(seq), self.pos))?,
);
}
// \{enclosing_char} - escaped
ch if enclosing_char == ch && !escape.is_empty() => {
escape.clear();
result.push(ch)
}
// Close wrapper
ch if enclosing_char == ch && escape.is_empty() => break,
// Unknown escape sequence
_ if !escape.is_empty() => {
return Err((LERR::MalformedEscapeSequence(escape), self.pos))
}
// Cannot have new-lines inside string literals
'\n' => {
self.rewind();
return Err((LERR::UnterminatedString, self.pos));
}
// All other characters
ch => {
escape.clear();
result.push(ch);
}
}
}
Ok(result.iter().collect())
}
/// Get the next token.
fn inner_next(&mut self) -> Option<(Token, Position)> {
let mut negated = false;
while let Some(c) = self.get_next() {
self.advance();
let pos = self.pos;
match (c, self.peek_next().unwrap_or('\0')) {
// \n
('\n', _) => self.new_line(),
// digit ...
('0'..='9', _) => {
let mut result = Vec::new();
let mut radix_base: Option<u32> = None;
result.push(c);
while let Some(next_char) = self.peek_next() {
match next_char {
'0'..='9' | '_' => {
result.push(next_char);
self.eat_next();
}
#[cfg(not(feature = "no_float"))]
'.' => {
result.push(next_char);
self.eat_next();
while let Some(next_char_in_float) = self.peek_next() {
match next_char_in_float {
'0'..='9' | '_' => {
result.push(next_char_in_float);
self.eat_next();
}
_ => break,
}
}
}
// 0x????, 0o????, 0b????
ch @ 'x' | ch @ 'X' | ch @ 'o' | ch @ 'O' | ch @ 'b' | ch @ 'B'
if c == '0' =>
{
result.push(next_char);
self.eat_next();
let valid = match ch {
'x' | 'X' => [
'a', 'b', 'c', 'd', 'e', 'f', 'A', 'B', 'C', 'D', 'E', 'F',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '_',
],
'o' | 'O' => [
'0', '1', '2', '3', '4', '5', '6', '7', '_', '_', '_', '_',
'_', '_', '_', '_', '_', '_', '_', '_', '_', '_', '_',
],
'b' | 'B' => [
'0', '1', '_', '_', '_', '_', '_', '_', '_', '_', '_', '_',
'_', '_', '_', '_', '_', '_', '_', '_', '_', '_', '_',
],
_ => panic!("unexpected character {}", ch),
};
radix_base = Some(match ch {
'x' | 'X' => 16,
'o' | 'O' => 8,
'b' | 'B' => 2,
_ => panic!("unexpected character {}", ch),
});
while let Some(next_char_in_hex) = self.peek_next() {
if !valid.contains(&next_char_in_hex) {
break;
}
result.push(next_char_in_hex);
self.eat_next();
}
}
_ => break,
}
}
if negated {
result.insert(0, '-');
}
// Parse number
if let Some(radix) = radix_base {
let out: String = result.iter().skip(2).filter(|&&c| c != '_').collect();
return Some((
INT::from_str_radix(&out, radix)
.map(Token::IntegerConstant)
.unwrap_or_else(|_| {
Token::LexError(Box::new(LERR::MalformedNumber(
result.iter().collect(),
)))
}),
pos,
));
} else {
let out: String = result.iter().filter(|&&c| c != '_').collect();
let num = INT::from_str(&out).map(Token::IntegerConstant);
// If integer parsing is unnecessary, try float instead
#[cfg(not(feature = "no_float"))]
let num = num.or_else(|_| FLOAT::from_str(&out).map(Token::FloatConstant));
return Some((
num.unwrap_or_else(|_| {
Token::LexError(Box::new(LERR::MalformedNumber(
result.iter().collect(),
)))
}),
pos,
));
}
}
// letter or underscore ...
('A'..='Z', _) | ('a'..='z', _) | ('_', _) => {
let mut result = Vec::new();
result.push(c);
while let Some(next_char) = self.peek_next() {
match next_char {
x if x.is_ascii_alphanumeric() || x == '_' => {
result.push(x);
self.eat_next();
}
_ => break,
}
}
let is_valid_identifier = result
.iter()
.find(|&ch| char::is_ascii_alphanumeric(ch)) // first alpha-numeric character
.map(char::is_ascii_alphabetic) // is a letter
.unwrap_or(false); // if no alpha-numeric at all - syntax error
let identifier: String = result.iter().collect();
if !is_valid_identifier {
return Some((
Token::LexError(Box::new(LERR::MalformedIdentifier(identifier))),
pos,
));
}
return Some((
match identifier.as_str() {
"true" => Token::True,
"false" => Token::False,
"let" => Token::Let,
"const" => Token::Const,
"if" => Token::If,
"else" => Token::Else,
"while" => Token::While,
"loop" => Token::Loop,
"continue" => Token::Continue,
"break" => Token::Break,
"return" => Token::Return,
"throw" => Token::Throw,
"for" => Token::For,
"in" => Token::In,
#[cfg(not(feature = "no_function"))]
"fn" => Token::Fn,
_ => Token::Identifier(identifier),
},
pos,
));
}
// " - string literal
('"', _) => {
return self.parse_string_literal('"').map_or_else(
|err| Some((Token::LexError(Box::new(err.0)), err.1)),
|out| Some((Token::StringConst(out), pos)),
);
}
// ' - character literal
('\'', '\'') => {
return Some((
Token::LexError(Box::new(LERR::MalformedChar("".to_string()))),
pos,
));
}
('\'', _) => {
return Some(self.parse_string_literal('\'').map_or_else(
|err| (Token::LexError(Box::new(err.0)), err.1),
|result| {
let mut chars = result.chars();
let first = chars.next();
if chars.next().is_some() {
(Token::LexError(Box::new(LERR::MalformedChar(result))), pos)
} else {
(Token::CharConstant(first.expect("should be Some")), pos)
}
},
));
}
// Braces
('{', _) => return Some((Token::LeftBrace, pos)),
('}', _) => return Some((Token::RightBrace, pos)),
// Parentheses
('(', _) => return Some((Token::LeftParen, pos)),
(')', _) => return Some((Token::RightParen, pos)),
// Indexing
('[', _) => return Some((Token::LeftBracket, pos)),
(']', _) => return Some((Token::RightBracket, pos)),
// Map literal
#[cfg(not(feature = "no_object"))]
('#', '{') => {
self.eat_next();
return Some((Token::MapStart, pos));
}
// Operators
('+', '=') => {
self.eat_next();
return Some((Token::PlusAssign, pos));
}
('+', _) if self.can_be_unary => return Some((Token::UnaryPlus, pos)),
('+', _) => return Some((Token::Plus, pos)),
('-', '0'..='9') if self.can_be_unary => negated = true,
('-', '0'..='9') => return Some((Token::Minus, pos)),
('-', '=') => {
self.eat_next();
return Some((Token::MinusAssign, pos));
}
('-', _) if self.can_be_unary => return Some((Token::UnaryMinus, pos)),
('-', _) => return Some((Token::Minus, pos)),
('*', '=') => {
self.eat_next();
return Some((Token::MultiplyAssign, pos));
}
('*', _) => return Some((Token::Multiply, pos)),
// Comments
('/', '/') => {
self.eat_next();
while let Some(c) = self.get_next() {
if c == '\n' {
self.new_line();
break;
}
self.advance();
}
}
('/', '*') => {
let mut level = 1;
self.eat_next();
while let Some(c) = self.get_next() {
self.advance();
match c {
'/' => {
if self.get_next() == Some('*') {
level += 1;
}
self.advance();
}
'*' => {
if self.get_next() == Some('/') {
level -= 1;
}
self.advance();
}
'\n' => self.new_line(),
_ => (),
}
if level == 0 {
break;
}
}
}
('/', '=') => {
self.eat_next();
return Some((Token::DivideAssign, pos));
}
('/', _) => return Some((Token::Divide, pos)),
(';', _) => return Some((Token::SemiColon, pos)),
(':', _) => return Some((Token::Colon, pos)),
(',', _) => return Some((Token::Comma, pos)),
('.', _) => return Some((Token::Period, pos)),
('=', '=') => {
self.eat_next();
return Some((Token::EqualsTo, pos));
}
('=', _) => return Some((Token::Equals, pos)),
('<', '=') => {
self.eat_next();
return Some((Token::LessThanEqualsTo, pos));
}
('<', '<') => {
self.eat_next();
return Some((
if self.peek_next() == Some('=') {
self.eat_next();
Token::LeftShiftAssign
} else {
Token::LeftShift
},
pos,
));
}
('<', _) => return Some((Token::LessThan, pos)),
('>', '=') => {
self.eat_next();
return Some((Token::GreaterThanEqualsTo, pos));
}
('>', '>') => {
self.eat_next();
return Some((
if self.peek_next() == Some('=') {
self.eat_next();
Token::RightShiftAssign
} else {
Token::RightShift
},
pos,
));
}
('>', _) => return Some((Token::GreaterThan, pos)),
('!', '=') => {
self.eat_next();
return Some((Token::NotEqualsTo, pos));
}
('!', _) => return Some((Token::Bang, pos)),
('|', '|') => {
self.eat_next();
return Some((Token::Or, pos));
}
('|', '=') => {
self.eat_next();
return Some((Token::OrAssign, pos));
}
('|', _) => return Some((Token::Pipe, pos)),
('&', '&') => {
self.eat_next();
return Some((Token::And, pos));
}
('&', '=') => {
self.eat_next();
return Some((Token::AndAssign, pos));
}
('&', _) => return Some((Token::Ampersand, pos)),
('^', '=') => {
self.eat_next();
return Some((Token::XOrAssign, pos));
}
('^', _) => return Some((Token::XOr, pos)),
('%', '=') => {
self.eat_next();
return Some((Token::ModuloAssign, pos));
}
('%', _) => return Some((Token::Modulo, pos)),
('~', '=') => {
self.eat_next();
return Some((Token::PowerOfAssign, pos));
}
('~', _) => return Some((Token::PowerOf, pos)),
(ch, _) if ch.is_whitespace() => (),
(ch, _) => return Some((Token::LexError(Box::new(LERR::UnexpectedChar(ch))), pos)),
}
}
None
}
}
impl<'a> Iterator for TokenIterator<'a> {
type Item = (Token, Position);
fn next(&mut self) -> Option<Self::Item> {
self.inner_next().map(|x| {
// Save the last token
self.can_be_unary = x.0.is_next_unary();
x
})
}
}
/// Tokenize an input text stream.
pub fn lex<'a>(input: &'a [&'a str]) -> TokenIterator<'a> {
TokenIterator {
can_be_unary: true,
pos: Position::new(1, 0),
streams: input.iter().map(|s| s.chars().peekable()).collect(),
}
}
/// Parse ( expr )
fn parse_paren_expr<'a>(
input: &mut Peekable<TokenIterator<'a>>,
begin: Position,
allow_stmt_expr: bool,
) -> Result<Expr, ParseError> {
if matches!(input.peek(), Some((Token::RightParen, _))) {
input.next();
return Ok(Expr::Unit(begin));
}
let expr = parse_expr(input, allow_stmt_expr)?;
match input.next() {
// ( xxx )
Some((Token::RightParen, _)) => Ok(expr),
// ( xxx ???
Some((_, pos)) => Err(PERR::MissingToken(
")".into(),
"for a matching ( in this expression".into(),
)
.into_err(pos)),
// ( xxx
None => Err(
PERR::MissingToken(")".into(), "for a matching ( in this expression".into())
.into_err_eof(),
),
}
}
/// Parse a function call.
fn parse_call_expr<'a, S: Into<Cow<'static, str>> + Display>(
id: S,
input: &mut Peekable<TokenIterator<'a>>,
begin: Position,
allow_stmt_expr: bool,
) -> Result<Expr, ParseError> {
let mut args_expr_list = Vec::new();
match input.peek() {
//id {EOF}
None => {
return Err(PERR::MissingToken(
")".into(),
format!("to close the arguments list of this function call '{}'", id),
)
.into_err_eof())
}
// id()
Some((Token::RightParen, _)) => {
input.next();
return Ok(Expr::FunctionCall(id.into(), args_expr_list, None, begin));
}
// id...
_ => (),
}
loop {
args_expr_list.push(parse_expr(input, allow_stmt_expr)?);
match input.peek() {
None => {
return Err(PERR::MissingToken(
")".into(),
format!("to close the arguments list of this function call '{}'", id),
)
.into_err_eof())
}
Some((Token::RightParen, _)) => {
input.next();
return Ok(Expr::FunctionCall(id.into(), args_expr_list, None, begin));
}
Some((Token::Comma, _)) => (),
Some((_, pos)) => {
return Err(PERR::MissingToken(
",".into(),
format!("to separate the arguments to function call '{}'", id),
)
.into_err(*pos))
}
}
input.next();
}
}
/// Parse an indexing expression.
fn parse_index_expr<'a>(
lhs: Box<Expr>,
input: &mut Peekable<TokenIterator<'a>>,
pos: Position,
allow_stmt_expr: bool,
) -> Result<Expr, ParseError> {
let idx_expr = parse_expr(input, allow_stmt_expr)?;
// Check type of indexing - must be integer or string
match &idx_expr {
// lhs[int]
Expr::IntegerConstant(i, pos) if *i < 0 => {
return Err(PERR::MalformedIndexExpr(format!(
"Array access expects non-negative index: {} < 0",
i
))
.into_err(*pos))
}
Expr::IntegerConstant(_, pos) => match *lhs {
Expr::Array(_, _) | Expr::StringConstant(_, _) => (),
Expr::Map(_, _) => {
return Err(PERR::MalformedIndexExpr(
"Object map access expects string index, not a number".into(),
)
.into_err(*pos))
}
Expr::FloatConstant(_, pos)
| Expr::CharConstant(_, pos)
| Expr::Assignment(_, _, pos)
| Expr::And(_, _, pos)
| Expr::Or(_, _, pos)
| Expr::In(_, _, pos)
| Expr::True(pos)
| Expr::False(pos)
| Expr::Unit(pos) => {
return Err(PERR::MalformedIndexExpr(
"Only arrays, object maps and strings can be indexed".into(),
)
.into_err(pos))
}
_ => (),
},
// lhs[string]
Expr::StringConstant(_, pos) => match *lhs {
Expr::Map(_, _) => (),
Expr::Array(_, _) | Expr::StringConstant(_, _) => {
return Err(PERR::MalformedIndexExpr(
"Array or string expects numeric index, not a string".into(),
)
.into_err(*pos))
}
Expr::FloatConstant(_, pos)
| Expr::CharConstant(_, pos)
| Expr::Assignment(_, _, pos)
| Expr::And(_, _, pos)
| Expr::Or(_, _, pos)
| Expr::In(_, _, pos)
| Expr::True(pos)
| Expr::False(pos)
| Expr::Unit(pos) => {
return Err(PERR::MalformedIndexExpr(
"Only arrays, object maps and strings can be indexed".into(),
)
.into_err(pos))
}
_ => (),
},
// lhs[float]
Expr::FloatConstant(_, pos) => {
return Err(PERR::MalformedIndexExpr(
"Array access expects integer index, not a float".into(),
)
.into_err(*pos))
}
// lhs[char]
Expr::CharConstant(_, pos) => {
return Err(PERR::MalformedIndexExpr(
"Array access expects integer index, not a character".into(),
)
.into_err(*pos))
}
// lhs[??? = ??? ], lhs[()]
Expr::Assignment(_, _, pos) | Expr::Unit(pos) => {
return Err(PERR::MalformedIndexExpr(
"Array access expects integer index, not ()".into(),
)
.into_err(*pos))
}
// lhs[??? && ???], lhs[??? || ???], lhs[??? in ???], lhs[true], lhs[false]
Expr::And(_, _, pos)
| Expr::Or(_, _, pos)
| Expr::In(_, _, pos)
| Expr::True(pos)
| Expr::False(pos) => {
return Err(PERR::MalformedIndexExpr(
"Array access expects integer index, not a boolean".into(),
)
.into_err(*pos))
}
// All other expressions
_ => (),
}
// Check if there is a closing bracket
match input.peek().ok_or_else(|| {
PERR::MissingToken(
"]".into(),
"for a matching [ in this index expression".into(),
)
.into_err_eof()
})? {
(Token::RightBracket, _) => {
input.next();
Ok(Expr::Index(lhs, Box::new(idx_expr), pos))
}
(_, pos) => Err(PERR::MissingToken(
"]".into(),
"for a matching [ in this index expression".into(),
)
.into_err(*pos)),
}
}
/// Parse an expression that begins with an identifier.
fn parse_ident_expr<'a, S: Into<Cow<'static, str>> + Display>(
id: S,
input: &mut Peekable<TokenIterator<'a>>,
begin: Position,
allow_stmt_expr: bool,
) -> Result<Expr, ParseError> {
match input.peek() {
// id(...) - function call
Some((Token::LeftParen, _)) => {
input.next();
parse_call_expr(id, input, begin, allow_stmt_expr)
}
// id[...] - indexing
#[cfg(not(feature = "no_index"))]
Some((Token::LeftBracket, pos)) => {
let pos = *pos;
input.next();
parse_index_expr(
Box::new(Expr::Variable(id.into(), begin)),
input,
pos,
allow_stmt_expr,
)
}
// id - variable
Some(_) => Ok(Expr::Variable(id.into(), begin)),
// EOF
None => Ok(Expr::Variable(id.into(), begin)),
}
}
/// Parse an array literal.
fn parse_array_literal<'a>(
input: &mut Peekable<TokenIterator<'a>>,
begin: Position,
allow_stmt_expr: bool,
) -> Result<Expr, ParseError> {
let mut arr = Vec::new();
if !matches!(input.peek(), Some((Token::RightBracket, _))) {
while input.peek().is_some() {
arr.push(parse_expr(input, allow_stmt_expr)?);
match input.peek().ok_or_else(|| {
PERR::MissingToken("]".into(), "to end this array literal".into()).into_err_eof()
})? {
(Token::Comma, _) => input.next(),
(Token::RightBracket, _) => break,
(_, pos) => {
return Err(PERR::MissingToken(
",".into(),
"to separate the items of this array literal".into(),
)
.into_err(*pos))
}
};
}
}
match input.peek().ok_or_else(|| {
PERR::MissingToken("]".into(), "to end this array literal".into()).into_err_eof()
})? {
(Token::RightBracket, _) => {
input.next();
Ok(Expr::Array(arr, begin))
}
(_, pos) => {
Err(PERR::MissingToken("]".into(), "to end this array literal".into()).into_err(*pos))
}
}
}
/// Parse a map literal.
fn parse_map_literal<'a>(
input: &mut Peekable<TokenIterator<'a>>,
begin: Position,
allow_stmt_expr: bool,
) -> Result<Expr, ParseError> {
let mut map = Vec::new();
if !matches!(input.peek(), Some((Token::RightBrace, _))) {
while input.peek().is_some() {
let (name, pos) = match input.next().ok_or_else(|| {
PERR::MissingToken("}".into(), "to end this object map literal".into())
.into_err_eof()
})? {
(Token::Identifier(s), pos) => (s, pos),
(Token::StringConst(s), pos) => (s, pos),
(_, pos) if map.is_empty() => {
return Err(PERR::MissingToken(
"}".into(),
"to end this object map literal".into(),
)
.into_err(pos))
}
(_, pos) => return Err(PERR::PropertyExpected.into_err(pos)),
};
match input.next().ok_or_else(|| {
PERR::MissingToken(
":".into(),
format!(
"to follow the property '{}' in this object map literal",
name
),
)
.into_err_eof()
})? {
(Token::Colon, _) => (),
(_, pos) => {
return Err(PERR::MissingToken(
":".into(),
format!(
"to follow the property '{}' in this object map literal",
name
),
)
.into_err(pos))
}
};
let expr = parse_expr(input, allow_stmt_expr)?;
map.push((name, expr, pos));
match input.peek().ok_or_else(|| {
PERR::MissingToken("}".into(), "to end this object map literal".into())
.into_err_eof()
})? {
(Token::Comma, _) => {
input.next();
}
(Token::RightBrace, _) => break,
(Token::Identifier(_), pos) => {
return Err(PERR::MissingToken(
",".into(),
"to separate the items of this object map literal".into(),
)
.into_err(*pos))
}
(_, pos) => {
return Err(PERR::MissingToken(
"}".into(),
"to end this object map literal".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))?;
// Ending brace
match input.peek().ok_or_else(|| {
PERR::MissingToken("}".into(), "to end this object map literal".into()).into_err_eof()
})? {
(Token::RightBrace, _) => {
input.next();
Ok(Expr::Map(map, begin))
}
(_, pos) => Err(
PERR::MissingToken("]".into(), "to end this object map literal".into()).into_err(*pos),
),
}
}
/// Parse a primary expression.
fn parse_primary<'a>(
input: &mut Peekable<TokenIterator<'a>>,
allow_stmt_expr: bool,
) -> Result<Expr, ParseError> {
let token = match input
.peek()
.ok_or_else(|| PERR::UnexpectedEOF.into_err_eof())?
{
// { - block statement as expression
(Token::LeftBrace, pos) if allow_stmt_expr => {
let pos = *pos;
return parse_block(input, false, allow_stmt_expr)
.map(|block| Expr::Stmt(Box::new(block), pos));
}
_ => input.next().expect("should be a token"),
};
let mut can_be_indexed = false;
let mut root_expr = match token {
(Token::IntegerConstant(x), pos) => Ok(Expr::IntegerConstant(x, pos)),
(Token::FloatConstant(x), pos) => Ok(Expr::FloatConstant(x, pos)),
(Token::CharConstant(c), pos) => Ok(Expr::CharConstant(c, pos)),
(Token::StringConst(s), pos) => {
can_be_indexed = true;
Ok(Expr::StringConstant(s.into(), pos))
}
(Token::Identifier(s), pos) => {
can_be_indexed = true;
parse_ident_expr(s, input, pos, allow_stmt_expr)
}
(Token::LeftParen, pos) => {
can_be_indexed = true;
parse_paren_expr(input, pos, allow_stmt_expr)
}
#[cfg(not(feature = "no_index"))]
(Token::LeftBracket, pos) => {
can_be_indexed = true;
parse_array_literal(input, pos, allow_stmt_expr)
}
#[cfg(not(feature = "no_object"))]
(Token::MapStart, pos) => {
can_be_indexed = true;
parse_map_literal(input, pos, allow_stmt_expr)
}
(Token::True, pos) => Ok(Expr::True(pos)),
(Token::False, pos) => Ok(Expr::False(pos)),
(Token::LexError(err), pos) => Err(PERR::BadInput(err.to_string()).into_err(pos)),
(token, pos) => {
Err(PERR::BadInput(format!("Unexpected '{}'", token.syntax())).into_err(pos))
}
}?;
#[cfg(feature = "no_index")]
let can_be_indexed = false;
if can_be_indexed {
// Tail processing all possible indexing
while let Some((Token::LeftBracket, pos)) = input.peek() {
let pos = *pos;
input.next();
root_expr = parse_index_expr(Box::new(root_expr), input, pos, allow_stmt_expr)?;
}
}
Ok(root_expr)
}
/// Parse a potential unary operator.
fn parse_unary<'a>(
input: &mut Peekable<TokenIterator<'a>>,
allow_stmt_expr: bool,
) -> Result<Expr, ParseError> {
match input
.peek()
.ok_or_else(|| PERR::UnexpectedEOF.into_err_eof())?
{
// If statement is allowed to act as expressions
(Token::If, pos) => {
let pos = *pos;
Ok(Expr::Stmt(
Box::new(parse_if(input, false, allow_stmt_expr)?),
pos,
))
}
// -expr
(Token::UnaryMinus, pos) => {
let pos = *pos;
input.next();
match parse_unary(input, allow_stmt_expr)? {
// Negative integer
Expr::IntegerConstant(i, _) => i
.checked_neg()
.map(|x| Expr::IntegerConstant(x, pos))
.or_else(|| {
#[cfg(not(feature = "no_float"))]
{
Some(Expr::FloatConstant(-(i as FLOAT), pos))
}
#[cfg(feature = "no_float")]
{
None
}
})
.ok_or_else(|| {
PERR::BadInput(LERR::MalformedNumber(format!("-{}", i)).to_string())
.into_err(pos)
}),
// Negative float
#[cfg(not(feature = "no_float"))]
Expr::FloatConstant(f, pos) => Ok(Expr::FloatConstant(-f, pos)),
// Call negative function
expr => Ok(Expr::FunctionCall("-".into(), vec![expr], None, pos)),
}
}
// +expr
(Token::UnaryPlus, _) => {
input.next();
parse_unary(input, allow_stmt_expr)
}
// !expr
(Token::Bang, pos) => {
let pos = *pos;
input.next();
Ok(Expr::FunctionCall(
"!".into(),
vec![parse_primary(input, allow_stmt_expr)?],
Some(Box::new(false)), // NOT operator, when operating on invalid operand, defaults to false
pos,
))
}
// All other tokens
_ => parse_primary(input, allow_stmt_expr),
}
}
/// Parse an assignment.
fn parse_assignment(lhs: Expr, rhs: Expr, pos: Position) -> Result<Expr, ParseError> {
// Is the LHS in a valid format for an assignment target?
fn valid_assignment_chain(expr: &Expr, is_top: bool) -> Option<ParseError> {
match expr {
// var
Expr::Variable(_, _) => {
assert!(is_top, "property expected but gets variable");
None
}
// property
Expr::Property(_, _) => {
assert!(!is_top, "variable expected but gets property");
None
}
// var[...]
Expr::Index(idx_lhs, _, _) if matches!(idx_lhs.as_ref(), &Expr::Variable(_, _)) => {
assert!(is_top, "property expected but gets variable");
None
}
// property[...]
Expr::Index(idx_lhs, _, _) if matches!(idx_lhs.as_ref(), &Expr::Property(_, _)) => {
assert!(!is_top, "variable expected but gets property");
None
}
// idx_lhs[...]
Expr::Index(idx_lhs, _, pos) => match idx_lhs.as_ref() {
Expr::Index(_, _, _) => Some(ParseErrorType::AssignmentToCopy.into_err(*pos)),
_ => Some(ParseErrorType::AssignmentToInvalidLHS.into_err(*pos)),
},
// dot_lhs.dot_rhs
Expr::Dot(dot_lhs, dot_rhs, _) => match dot_lhs.as_ref() {
// var.dot_rhs
Expr::Variable(_, _) if is_top => valid_assignment_chain(dot_rhs, false),
// property.dot_rhs
Expr::Property(_, _) if !is_top => valid_assignment_chain(dot_rhs, false),
// var[...]
Expr::Index(idx_lhs, _, _)
if matches!(idx_lhs.as_ref(), &Expr::Variable(_, _)) && is_top =>
{
valid_assignment_chain(dot_rhs, false)
}
// property[...]
Expr::Index(idx_lhs, _, _)
if matches!(idx_lhs.as_ref(), &Expr::Property(_, _)) && !is_top =>
{
valid_assignment_chain(dot_rhs, false)
}
// idx_lhs[...]
Expr::Index(idx_lhs, _, _) => {
Some(ParseErrorType::AssignmentToCopy.into_err(idx_lhs.position()))
}
expr => panic!("unexpected dot expression {:#?}", expr),
},
_ => Some(ParseErrorType::AssignmentToInvalidLHS.into_err(expr.position())),
}
}
match valid_assignment_chain(&lhs, true) {
None => Ok(Expr::Assignment(Box::new(lhs), Box::new(rhs), pos)),
Some(err) => Err(err),
}
}
/// Parse an operator-assignment expression.
fn parse_op_assignment<S: Into<Cow<'static, str>>>(
op: S,
lhs: Expr,
rhs: Expr,
pos: Position,
) -> Result<Expr, ParseError> {
let lhs_copy = lhs.clone();
// lhs op= rhs -> lhs = op(lhs, rhs)
parse_assignment(
lhs,
Expr::FunctionCall(op.into(), vec![lhs_copy, rhs], None, pos),
pos,
)
}
/// Parse an 'in' expression.
fn parse_in_expr(lhs: Expr, rhs: Expr, op_pos: Position) -> Result<Expr, ParseError> {
match (&lhs, &rhs) {
(_, Expr::IntegerConstant(_, pos))
| (_, Expr::FloatConstant(_, pos))
| (_, Expr::And(_, _, pos))
| (_, Expr::Or(_, _, pos))
| (_, Expr::In(_, _, pos))
| (_, Expr::True(pos))
| (_, Expr::False(pos))
| (_, Expr::Assignment(_, _, pos))
| (_, Expr::Unit(pos)) => {
return Err(PERR::MalformedInExpr(
"'in' expression expects a string, array or object map".into(),
)
.into_err(*pos))
}
// "xxx" in "xxxx", 'x' in "xxxx" - OK!
(Expr::StringConstant(_, _), Expr::StringConstant(_, _))
| (Expr::CharConstant(_, _), Expr::StringConstant(_, _)) => (),
// 123.456 in "xxxx"
(Expr::FloatConstant(_, pos), Expr::StringConstant(_, _)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for a string expects a string, not a float".into(),
)
.into_err(*pos))
}
// 123 in "xxxx"
(Expr::IntegerConstant(_, pos), Expr::StringConstant(_, _)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for a string expects a string, not a number".into(),
)
.into_err(*pos))
}
// (??? && ???) in "xxxx", (??? || ???) in "xxxx", (??? in ???) in "xxxx",
// true in "xxxx", false in "xxxx"
(Expr::And(_, _, pos), Expr::StringConstant(_, _))
| (Expr::Or(_, _, pos), Expr::StringConstant(_, _))
| (Expr::In(_, _, pos), Expr::StringConstant(_, _))
| (Expr::True(pos), Expr::StringConstant(_, _))
| (Expr::False(pos), Expr::StringConstant(_, _)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for a string expects a string, not a boolean".into(),
)
.into_err(*pos))
}
// [???, ???, ???] in "xxxx"
(Expr::Array(_, pos), Expr::StringConstant(_, _)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for a string expects a string, not an array".into(),
)
.into_err(*pos))
}
// #{...} in "xxxx"
(Expr::Map(_, pos), Expr::StringConstant(_, _)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for a string expects a string, not an object map".into(),
)
.into_err(*pos))
}
// (??? = ???) in "xxxx", () in "xxxx"
(Expr::Assignment(_, _, pos), Expr::StringConstant(_, _))
| (Expr::Unit(pos), Expr::StringConstant(_, _)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for a string expects a string, not ()".into(),
)
.into_err(*pos))
}
// "xxx" in #{...}, 'x' in #{...} - OK!
(Expr::StringConstant(_, _), Expr::Map(_, _))
| (Expr::CharConstant(_, _), Expr::Map(_, _)) => (),
// 123.456 in #{...}
(Expr::FloatConstant(_, pos), Expr::Map(_, _)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for an object map expects a string, not a float".into(),
)
.into_err(*pos))
}
// 123 in #{...}
(Expr::IntegerConstant(_, pos), Expr::Map(_, _)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for an object map expects a string, not a number".into(),
)
.into_err(*pos))
}
// (??? && ???) in #{...}, (??? || ???) in #{...}, (??? in ???) in #{...},
// true in #{...}, false in #{...}
(Expr::And(_, _, pos), Expr::Map(_, _))
| (Expr::Or(_, _, pos), Expr::Map(_, _))
| (Expr::In(_, _, pos), Expr::Map(_, _))
| (Expr::True(pos), Expr::Map(_, _))
| (Expr::False(pos), Expr::Map(_, _)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for an object map expects a string, not a boolean".into(),
)
.into_err(*pos))
}
// [???, ???, ???] in #{..}
(Expr::Array(_, pos), Expr::Map(_, _)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for an object map expects a string, not an array".into(),
)
.into_err(*pos))
}
// #{...} in #{..}
(Expr::Map(_, pos), Expr::Map(_, _)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for an object map expects a string, not an object map".into(),
)
.into_err(*pos))
}
// (??? = ???) in #{...}, () in #{...}
(Expr::Assignment(_, _, pos), Expr::Map(_, _)) | (Expr::Unit(pos), Expr::Map(_, _)) => {
return Err(PERR::MalformedInExpr(
"'in' expression for an object map expects a string, not ()".into(),
)
.into_err(*pos))
}
_ => (),
}
Ok(Expr::In(Box::new(lhs), Box::new(rhs), op_pos))
}
/// Parse a binary expression.
fn parse_binary_op<'a>(
input: &mut Peekable<TokenIterator<'a>>,
parent_precedence: u8,
lhs: Expr,
allow_stmt_expr: bool,
) -> Result<Expr, ParseError> {
let mut current_lhs = lhs;
loop {
let (current_precedence, bind_right) = input.peek().map_or_else(
|| (0, false),
|(current_op, _)| (current_op.precedence(), 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 current_precedence < parent_precedence
|| (current_precedence == parent_precedence && !bind_right)
{
return Ok(current_lhs);
}
if let Some((op_token, pos)) = input.next() {
input.peek();
let rhs = parse_unary(input, allow_stmt_expr)?;
let next_precedence = if let Some((next_op, _)) = input.peek() {
next_op.precedence()
} else {
0
};
// Bind to right if the next operator has higher precedence
// If same precedence, then check if the operator binds right
let rhs = if (current_precedence == next_precedence && bind_right)
|| current_precedence < next_precedence
{
parse_binary_op(input, current_precedence, rhs, allow_stmt_expr)?
} else {
// Otherwise bind to left (even if next operator has the same precedence)
rhs
};
current_lhs = match op_token {
Token::Plus => Expr::FunctionCall("+".into(), vec![current_lhs, rhs], None, pos),
Token::Minus => Expr::FunctionCall("-".into(), vec![current_lhs, rhs], None, pos),
Token::Multiply => {
Expr::FunctionCall("*".into(), vec![current_lhs, rhs], None, pos)
}
Token::Divide => Expr::FunctionCall("/".into(), vec![current_lhs, rhs], None, pos),
Token::Equals => parse_assignment(current_lhs, rhs, pos)?,
Token::PlusAssign => parse_op_assignment("+", current_lhs, rhs, pos)?,
Token::MinusAssign => parse_op_assignment("-", current_lhs, rhs, pos)?,
#[cfg(not(feature = "no_object"))]
Token::Period => {
fn check_property(expr: Expr) -> Result<Expr, ParseError> {
match expr {
// xxx.lhs.rhs
Expr::Dot(lhs, rhs, pos) => Ok(Expr::Dot(
Box::new(check_property(*lhs)?),
Box::new(check_property(*rhs)?),
pos,
)),
// xxx.lhs[idx]
Expr::Index(lhs, idx, pos) => {
Ok(Expr::Index(Box::new(check_property(*lhs)?), idx, pos))
}
// xxx.id
Expr::Variable(id, pos) => Ok(Expr::Property(id, pos)),
// xxx.prop
expr @ Expr::Property(_, _) => Ok(expr),
// xxx.fn()
expr @ Expr::FunctionCall(_, _, _, _) => Ok(expr),
expr => Err(PERR::PropertyExpected.into_err(expr.position())),
}
}
Expr::Dot(Box::new(current_lhs), Box::new(check_property(rhs)?), pos)
}
// Comparison operators default to false when passed invalid operands
Token::EqualsTo => Expr::FunctionCall(
"==".into(),
vec![current_lhs, rhs],
Some((false).into_dynamic()),
pos,
),
Token::NotEqualsTo => Expr::FunctionCall(
"!=".into(),
vec![current_lhs, rhs],
Some((false).into_dynamic()),
pos,
),
Token::LessThan => Expr::FunctionCall(
"<".into(),
vec![current_lhs, rhs],
Some((false).into_dynamic()),
pos,
),
Token::LessThanEqualsTo => Expr::FunctionCall(
"<=".into(),
vec![current_lhs, rhs],
Some((false).into_dynamic()),
pos,
),
Token::GreaterThan => Expr::FunctionCall(
">".into(),
vec![current_lhs, rhs],
Some((false).into_dynamic()),
pos,
),
Token::GreaterThanEqualsTo => Expr::FunctionCall(
">=".into(),
vec![current_lhs, rhs],
Some((false).into_dynamic()),
pos,
),
Token::Or => Expr::Or(Box::new(current_lhs), Box::new(rhs), pos),
Token::And => Expr::And(Box::new(current_lhs), Box::new(rhs), pos),
Token::In => parse_in_expr(current_lhs, rhs, pos)?,
Token::XOr => Expr::FunctionCall("^".into(), vec![current_lhs, rhs], None, pos),
Token::OrAssign => parse_op_assignment("|", current_lhs, rhs, pos)?,
Token::AndAssign => parse_op_assignment("&", current_lhs, rhs, pos)?,
Token::XOrAssign => parse_op_assignment("^", current_lhs, rhs, pos)?,
Token::MultiplyAssign => parse_op_assignment("*", current_lhs, rhs, pos)?,
Token::DivideAssign => parse_op_assignment("/", current_lhs, rhs, pos)?,
Token::Pipe => Expr::FunctionCall("|".into(), vec![current_lhs, rhs], None, pos),
Token::LeftShift => {
Expr::FunctionCall("<<".into(), vec![current_lhs, rhs], None, pos)
}
Token::RightShift => {
Expr::FunctionCall(">>".into(), vec![current_lhs, rhs], None, pos)
}
Token::LeftShiftAssign => parse_op_assignment("<<", current_lhs, rhs, pos)?,
Token::RightShiftAssign => parse_op_assignment(">>", current_lhs, rhs, pos)?,
Token::Ampersand => {
Expr::FunctionCall("&".into(), vec![current_lhs, rhs], None, pos)
}
Token::Modulo => Expr::FunctionCall("%".into(), vec![current_lhs, rhs], None, pos),
Token::ModuloAssign => parse_op_assignment("%", current_lhs, rhs, pos)?,
Token::PowerOf => Expr::FunctionCall("~".into(), vec![current_lhs, rhs], None, pos),
Token::PowerOfAssign => parse_op_assignment("~", current_lhs, rhs, pos)?,
token => return Err(PERR::UnknownOperator(token.syntax().into()).into_err(pos)),
};
}
}
}
/// Parse an expression.
fn parse_expr<'a>(
input: &mut Peekable<TokenIterator<'a>>,
allow_stmt_expr: bool,
) -> Result<Expr, ParseError> {
// Parse a real expression
let lhs = parse_unary(input, allow_stmt_expr)?;
parse_binary_op(input, 1, lhs, allow_stmt_expr)
}
/// Make sure that the expression is not a statement expression (i.e. wrapped in {})
fn ensure_not_statement_expr<'a>(
input: &mut Peekable<TokenIterator<'a>>,
type_name: &str,
) -> Result<(), ParseError> {
match input
.peek()
.ok_or_else(|| PERR::ExprExpected(type_name.to_string()).into_err_eof())?
{
// Disallow statement expressions
(Token::LeftBrace, 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(()),
}
}
/// Parse an if statement.
fn parse_if<'a>(
input: &mut Peekable<TokenIterator<'a>>,
breakable: bool,
allow_stmt_expr: bool,
) -> Result<Stmt, ParseError> {
// if ...
input.next();
// if guard { if_body }
ensure_not_statement_expr(input, "a boolean")?;
let guard = parse_expr(input, allow_stmt_expr)?;
let if_body = parse_block(input, breakable, allow_stmt_expr)?;
// if guard { if_body } else ...
let else_body = if matches!(input.peek(), Some((Token::Else, _))) {
input.next();
Some(Box::new(if matches!(input.peek(), Some((Token::If, _))) {
// if guard { if_body } else if ...
parse_if(input, breakable, allow_stmt_expr)?
} else {
// if guard { if_body } else { else-body }
parse_block(input, breakable, allow_stmt_expr)?
}))
} else {
None
};
Ok(Stmt::IfThenElse(
Box::new(guard),
Box::new(if_body),
else_body,
))
}
/// Parse a while loop.
fn parse_while<'a>(
input: &mut Peekable<TokenIterator<'a>>,
allow_stmt_expr: bool,
) -> Result<Stmt, ParseError> {
// while ...
input.next();
// while guard { body }
ensure_not_statement_expr(input, "a boolean")?;
let guard = parse_expr(input, allow_stmt_expr)?;
let body = parse_block(input, true, allow_stmt_expr)?;
Ok(Stmt::While(Box::new(guard), Box::new(body)))
}
/// Parse a loop statement.
fn parse_loop<'a>(
input: &mut Peekable<TokenIterator<'a>>,
allow_stmt_expr: bool,
) -> Result<Stmt, ParseError> {
// loop ...
input.next();
// loop { body }
let body = parse_block(input, true, allow_stmt_expr)?;
Ok(Stmt::Loop(Box::new(body)))
}
/// Parse a for loop.
fn parse_for<'a>(
input: &mut Peekable<TokenIterator<'a>>,
allow_stmt_expr: bool,
) -> Result<Stmt, ParseError> {
// for ...
input.next();
// for name ...
let name = match input
.next()
.ok_or_else(|| PERR::VariableExpected.into_err_eof())?
{
// Variable name
(Token::Identifier(s), _) => s,
// Bad identifier
(Token::LexError(err), pos) => return Err(PERR::BadInput(err.to_string()).into_err(pos)),
// Not a variable name
(_, pos) => return Err(PERR::VariableExpected.into_err(pos)),
};
// for name in ...
match input.next().ok_or_else(|| {
PERR::MissingToken("in".into(), "after the iteration variable".into()).into_err_eof()
})? {
(Token::In, _) => (),
(_, pos) => {
return Err(
PERR::MissingToken("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, allow_stmt_expr)?;
let body = parse_block(input, true, allow_stmt_expr)?;
Ok(Stmt::For(name.into(), Box::new(expr), Box::new(body)))
}
/// Parse a variable definition statement.
fn parse_let<'a>(
input: &mut Peekable<TokenIterator<'a>>,
var_type: ScopeEntryType,
allow_stmt_expr: bool,
) -> Result<Stmt, ParseError> {
// let/const... (specified in `var_type`)
input.next();
// let name ...
let (name, pos) = match input
.next()
.ok_or_else(|| PERR::VariableExpected.into_err_eof())?
{
(Token::Identifier(s), pos) => (s, pos),
(Token::LexError(err), pos) => return Err(PERR::BadInput(err.to_string()).into_err(pos)),
(_, pos) => return Err(PERR::VariableExpected.into_err(pos)),
};
// let name = ...
if matches!(input.peek(), Some((Token::Equals, _))) {
input.next();
// let name = expr
let init_value = parse_expr(input, allow_stmt_expr)?;
match var_type {
// let name = expr
ScopeEntryType::Normal => Ok(Stmt::Let(name.into(), Some(Box::new(init_value)), pos)),
// const name = { expr:constant }
ScopeEntryType::Constant if init_value.is_constant() => {
Ok(Stmt::Const(name.into(), Box::new(init_value), pos))
}
// const name = expr - error
ScopeEntryType::Constant => {
Err(PERR::ForbiddenConstantExpr(name).into_err(init_value.position()))
}
}
} else {
// let name
Ok(Stmt::Let(name.into(), None, pos))
}
}
/// Parse a statement block.
fn parse_block<'a>(
input: &mut Peekable<TokenIterator<'a>>,
breakable: bool,
allow_stmt_expr: bool,
) -> Result<Stmt, ParseError> {
// Must start with {
let pos = match input
.next()
.ok_or_else(|| PERR::UnexpectedEOF.into_err_eof())?
{
(Token::LeftBrace, pos) => pos,
(_, pos) => {
return Err(
PERR::MissingToken("{".into(), "to start a statement block".into()).into_err(pos),
)
}
};
let mut statements = Vec::new();
while !matches!(input.peek(), Some((Token::RightBrace, _))) {
// Parse statements inside the block
let stmt = parse_stmt(input, breakable, allow_stmt_expr)?;
// See if it needs a terminating semicolon
let need_semicolon = !stmt.is_self_terminated();
statements.push(stmt);
match input.peek() {
// EOF
None => break,
// { ... stmt }
Some((Token::RightBrace, _)) => break,
// { ... stmt;
Some((Token::SemiColon, _)) if need_semicolon => {
input.next();
}
// { ... { stmt } ;
Some((Token::SemiColon, _)) if !need_semicolon => (),
// { ... { stmt } ???
Some((_, _)) if !need_semicolon => (),
// { ... stmt ??? - error
Some((_, pos)) => {
// Semicolons are not optional between statements
return Err(
PERR::MissingToken(";".into(), "to terminate this statement".into())
.into_err(*pos),
);
}
}
}
match input.peek().ok_or_else(|| {
PERR::MissingToken("}".into(), "to end this statement block".into()).into_err_eof()
})? {
(Token::RightBrace, _) => {
input.next();
Ok(Stmt::Block(statements, pos))
}
(_, pos) => {
Err(PERR::MissingToken("}".into(), "to end this statement block".into()).into_err(*pos))
}
}
}
/// Parse an expression as a statement.
fn parse_expr_stmt<'a>(
input: &mut Peekable<TokenIterator<'a>>,
allow_stmt_expr: bool,
) -> Result<Stmt, ParseError> {
Ok(Stmt::Expr(Box::new(parse_expr(input, allow_stmt_expr)?)))
}
/// Parse a single statement.
fn parse_stmt<'a>(
input: &mut Peekable<TokenIterator<'a>>,
breakable: bool,
allow_stmt_expr: bool,
) -> Result<Stmt, ParseError> {
let token = match input.peek() {
Some(token) => token,
None => return Ok(Stmt::Noop(Position::eof())),
};
match token {
// Semicolon - empty statement
(Token::SemiColon, pos) => Ok(Stmt::Noop(*pos)),
(Token::LeftBrace, _) => parse_block(input, breakable, allow_stmt_expr),
// fn ...
#[cfg(not(feature = "no_function"))]
(Token::Fn, pos) => Err(PERR::WrongFnDefinition.into_err(*pos)),
(Token::If, _) => parse_if(input, breakable, allow_stmt_expr),
(Token::While, _) => parse_while(input, allow_stmt_expr),
(Token::Loop, _) => parse_loop(input, allow_stmt_expr),
(Token::For, _) => parse_for(input, allow_stmt_expr),
(Token::Continue, pos) if breakable => {
let pos = *pos;
input.next();
Ok(Stmt::Continue(pos))
}
(Token::Break, pos) if breakable => {
let pos = *pos;
input.next();
Ok(Stmt::Break(pos))
}
(Token::Continue, pos) | (Token::Break, pos) => Err(PERR::LoopBreak.into_err(*pos)),
(token @ Token::Return, pos) | (token @ Token::Throw, pos) => {
let return_type = match token {
Token::Return => ReturnType::Return,
Token::Throw => ReturnType::Exception,
_ => panic!("token should be return or throw"),
};
let pos = *pos;
input.next();
match input.peek() {
// `return`/`throw` at EOF
None => Ok(Stmt::ReturnWithVal(None, return_type, Position::eof())),
// `return;` or `throw;`
Some((Token::SemiColon, _)) => Ok(Stmt::ReturnWithVal(None, return_type, pos)),
// `return` or `throw` with expression
Some((_, _)) => {
let expr = parse_expr(input, allow_stmt_expr)?;
let pos = expr.position();
Ok(Stmt::ReturnWithVal(Some(Box::new(expr)), return_type, pos))
}
}
}
(Token::Let, _) => parse_let(input, ScopeEntryType::Normal, allow_stmt_expr),
(Token::Const, _) => parse_let(input, ScopeEntryType::Constant, allow_stmt_expr),
_ => parse_expr_stmt(input, allow_stmt_expr),
}
}
/// Parse a function definition.
fn parse_fn<'a>(
input: &mut Peekable<TokenIterator<'a>>,
allow_stmt_expr: bool,
) -> Result<FnDef, ParseError> {
let pos = input.next().expect("should be fn").1;
let name = match input
.next()
.ok_or_else(|| PERR::FnMissingName.into_err_eof())?
{
(Token::Identifier(s), _) => s,
(_, pos) => return Err(PERR::FnMissingName.into_err(pos)),
};
match input
.peek()
.ok_or_else(|| PERR::FnMissingParams(name.clone()).into_err_eof())?
{
(Token::LeftParen, _) => input.next(),
(_, pos) => return Err(PERR::FnMissingParams(name).into_err(*pos)),
};
let mut params = Vec::new();
if matches!(input.peek(), Some((Token::RightParen, _))) {
input.next();
} else {
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
.next()
.ok_or_else(|| PERR::MissingToken(")".into(), end_err.to_string()).into_err_eof())?
{
(Token::Identifier(s), pos) => params.push((s, pos)),
(_, pos) => return Err(PERR::MissingToken(")".into(), end_err).into_err(pos)),
}
match input
.next()
.ok_or_else(|| PERR::MissingToken(")".into(), end_err.to_string()).into_err_eof())?
{
(Token::RightParen, _) => break,
(Token::Comma, _) => (),
(Token::Identifier(_), pos) => {
return Err(PERR::MissingToken(",".into(), sep_err).into_err(pos))
}
(_, pos) => return Err(PERR::MissingToken(",".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() {
Some((Token::LeftBrace, _)) => parse_block(input, false, allow_stmt_expr)?,
Some((_, pos)) => return Err(PERR::FnMissingBody(name).into_err(*pos)),
None => return Err(PERR::FnMissingBody(name).into_err_eof()),
};
let params = params.into_iter().map(|(p, _)| p).collect();
Ok(FnDef {
name,
params,
body,
pos,
})
}
pub fn parse_global_expr<'a, 'e>(
input: &mut Peekable<TokenIterator<'a>>,
engine: &Engine<'e>,
scope: &Scope,
optimization_level: OptimizationLevel,
) -> Result<AST, ParseError> {
let expr = parse_expr(input, false)?;
if let Some((token, pos)) = input.peek() {
// Return error if the expression doesn't end
return Err(PERR::BadInput(format!("Unexpected '{}'", token.syntax())).into_err(*pos));
}
Ok(
// Optimize AST
optimize_into_ast(
engine,
scope,
vec![Stmt::Expr(Box::new(expr))],
vec![],
optimization_level,
),
)
}
/// Parse the global level statements.
fn parse_global_level<'a>(
input: &mut Peekable<TokenIterator<'a>>,
) -> Result<(Vec<Stmt>, Vec<FnDef>), ParseError> {
let mut statements = Vec::<Stmt>::new();
let mut functions = Vec::<FnDef>::new();
while input.peek().is_some() {
// Collect all the function definitions
#[cfg(not(feature = "no_function"))]
{
if matches!(input.peek().expect("should not be None"), (Token::Fn, _)) {
let f = parse_fn(input, true)?;
// Ensure list is sorted
match functions.binary_search_by(|fn_def| fn_def.compare(&f.name, f.params.len())) {
Ok(n) => functions[n] = f, // Override previous definition
Err(n) => functions.insert(n, f), // New function definition
}
continue;
}
}
// Actual statement
let stmt = parse_stmt(input, false, true)?;
let need_semicolon = !stmt.is_self_terminated();
statements.push(stmt);
match input.peek() {
// EOF
None => break,
// stmt ;
Some((Token::SemiColon, _)) if need_semicolon => {
input.next();
}
// stmt ;
Some((Token::SemiColon, _)) if !need_semicolon => (),
// { stmt } ???
Some((_, _)) if !need_semicolon => (),
// stmt ??? - error
Some((_, pos)) => {
// Semicolons are not optional between statements
return Err(
PERR::MissingToken(";".into(), "to terminate this statement".into())
.into_err(*pos),
);
}
}
}
Ok((statements, functions))
}
/// Run the parser on an input stream, returning an AST.
pub fn parse<'a, 'e>(
input: &mut Peekable<TokenIterator<'a>>,
engine: &Engine<'e>,
scope: &Scope,
optimization_level: OptimizationLevel,
) -> Result<AST, ParseError> {
let (statements, functions) = parse_global_level(input)?;
Ok(
// Optimize AST
optimize_into_ast(engine, scope, statements, functions, 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> {
if value.is::<INT>() {
Some(Expr::IntegerConstant(value.cast(), pos))
} else if value.is::<char>() {
Some(Expr::CharConstant(value.cast(), pos))
} else if value.is::<String>() {
Some(Expr::StringConstant(value.cast::<String>().into(), pos))
} else if value.is::<bool>() {
Some(if value.cast::<bool>() {
Expr::True(pos)
} else {
Expr::False(pos)
})
} else {
#[cfg(not(feature = "no_index"))]
{
if value.is::<Array>() {
let array = value.cast::<Array>();
let items: Vec<_> = array
.into_iter()
.map(|x| map_dynamic_to_expr(x, pos))
.collect();
if items.iter().all(Option::is_some) {
return Some(Expr::Array(
items.into_iter().map(Option::unwrap).collect(),
pos,
));
} else {
return None;
}
}
}
#[cfg(not(feature = "no_object"))]
{
if value.is::<Map>() {
let map = value.cast::<Map>();
let items: Vec<_> = map
.into_iter()
.map(|(k, v)| (k, map_dynamic_to_expr(v, pos), pos))
.collect();
if items.iter().all(|(_, expr, _)| expr.is_some()) {
return Some(Expr::Map(
items
.into_iter()
.map(|(k, expr, pos)| (k, expr.unwrap(), pos))
.collect(),
pos,
));
} else {
return None;
}
}
}
#[cfg(not(feature = "no_float"))]
{
if value.is::<FLOAT>() {
return Some(Expr::FloatConstant(value.cast(), pos));
}
}
None
}
}
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