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Enable more indexing expressions.

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This commit is contained in:
Stephen Chung 2020-03-05 20:28:03 +08:00
parent c9395049e2
commit 883f08c026
4 changed files with 230 additions and 123 deletions
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30
README.md
View File

@ -11,7 +11,7 @@ Rhai's current feature set:
* Support for overloaded functions
* No additional dependencies
**Note:** Currently, the version is 0.10.1, so the language and API may change before they stabilize.
**Note:** Currently, the version is 0.10.1, so the language and API's may change before they stabilize.
## Installation
@ -585,7 +585,7 @@ return 123 + 456;
```rust
if error != "" {
throw error; // `throw` takes a string to form the exception text
throw error; // 'throw' takes a string to form the exception text
}
throw; // no exception text
@ -628,12 +628,19 @@ y[1] = 42;
print(y[1]); // prints 42
ts.list = y; // arrays can be assigned completely (by value copy)
let foo = ts.list[1]; // indexing into properties is ok
let foo = ts.list[1];
foo == 42;
let foo = [1, 2, 3][0]; // a syntax error (for now) - cannot index into literals
let foo = abc()[0]; // a syntax error (for now) - cannot index into function call return values
let foo = y[0]; // this works
let foo = [1, 2, 3][0];
foo == 1;
fn abc() { [42, 43, 44] }
let foo = abc()[0];
foo == 42;
let foo = y[0];
foo == 1;
y.push(4); // 4 elements
y.push(5); // 5 elements
@ -734,14 +741,19 @@ let c = record[4];
c == 'C';
ts.s = record;
let c = ts.s[4]; // indexing into properties is ok
let c = ts.s[4];
c == 'C';
let c = "foo"[0]; // a syntax error (for now) - cannot index into literals
let c = "foo"[0];
c == 'f';
let c = ("foo" + "bar")[5];
c == 'r';
// Escape sequences in strings
record += " \u2764\n"; // escape sequence of '❤' in Unicode
record == "Bob C. Davis: age 42 ❤\n"; // '\n' = new-line
record == "Bob C. Davis: age 42 ❤\n"; // '\n' = new-line
// Unlike Rust, Rhai strings can be modified
record[4] = '\x58'; // 0x58 = 'X'

243
src/engine.rs
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@ -18,6 +18,13 @@ const KEYWORD_PRINT: &'static str = "print";
const KEYWORD_DEBUG: &'static str = "debug";
const KEYWORD_TYPE_OF: &'static str = "type_of";
#[derive(Copy, Clone, Debug, Eq, Hash, PartialEq, PartialOrd, Ord)]
enum VariableType {
Array,
String,
Expression,
}
#[derive(Clone, Debug, Eq, Hash, PartialEq, PartialOrd, Ord)]
pub struct FnSpec<'a> {
pub name: Cow<'a, str>,
@ -193,15 +200,24 @@ impl Engine<'_> {
self.call_fn_raw(&get_fn_name, vec![this_ptr], None, *pos)
}
Expr::Index(id, idx_expr, pos) => {
Expr::Index(lhs, idx_expr) => {
let idx = *self
.eval_expr(scope, idx_expr)?
.downcast::<i64>()
.map_err(|_| EvalAltResult::ErrorIndexExpr(idx_expr.position()))?;
let get_fn_name = format!("get${}", id);
let val = self.call_fn_raw(&get_fn_name, vec![this_ptr], None, *pos)?;
Self::get_indexed_value(val, idx, *pos).map(|(v, _)| v)
let (lhs_value, pos) = match lhs.as_ref() {
Expr::Identifier(id, pos) => {
let get_fn_name = format!("get${}", id);
(
self.call_fn_raw(&get_fn_name, vec![this_ptr], None, *pos)?,
*pos,
)
}
expr => return Err(EvalAltResult::ErrorDotExpr(expr.position())),
};
Self::get_indexed_value(lhs_value, idx, pos).map(|(v, _)| v)
}
Expr::Dot(inner_lhs, inner_rhs) => match inner_lhs.as_ref() {
@ -211,16 +227,25 @@ impl Engine<'_> {
self.call_fn_raw(&get_fn_name, vec![this_ptr], None, *pos)
.and_then(|mut v| self.get_dot_val_helper(scope, v.as_mut(), inner_rhs))
}
Expr::Index(id, idx_expr, pos) => {
Expr::Index(lhs, idx_expr) => {
let idx = *self
.eval_expr(scope, idx_expr)?
.downcast::<i64>()
.map_err(|_| EvalAltResult::ErrorIndexExpr(idx_expr.position()))?;
let get_fn_name = format!("get${}", id);
let val = self.call_fn_raw(&get_fn_name, vec![this_ptr], None, *pos)?;
Self::get_indexed_value(val, idx, *pos).and_then(|(mut v, _)| {
self.get_dot_val_helper(scope, v.as_mut(), inner_rhs)
let (lhs_value, pos) = match lhs.as_ref() {
Expr::Identifier(id, pos) => {
let get_fn_name = format!("get${}", id);
(
self.call_fn_raw(&get_fn_name, vec![this_ptr], None, *pos)?,
*pos,
)
}
expr => return Err(EvalAltResult::ErrorDotExpr(expr.position())),
};
Self::get_indexed_value(lhs_value, idx, pos).and_then(|(mut value, _)| {
self.get_dot_val_helper(scope, value.as_mut(), inner_rhs)
})
}
_ => Err(EvalAltResult::ErrorDotExpr(inner_lhs.position())),
@ -246,14 +271,14 @@ impl Engine<'_> {
val: Dynamic,
idx: i64,
pos: Position,
) -> Result<(Dynamic, bool), EvalAltResult> {
) -> Result<(Dynamic, VariableType), EvalAltResult> {
if val.is::<Array>() {
let arr = val.downcast::<Array>().unwrap();
if idx >= 0 {
arr.get(idx as usize)
.cloned()
.map(|v| (v, true))
.map(|v| (v, VariableType::Array))
.ok_or_else(|| EvalAltResult::ErrorArrayBounds(arr.len(), idx, pos))
} else {
Err(EvalAltResult::ErrorArrayBounds(arr.len(), idx, pos))
@ -264,7 +289,7 @@ impl Engine<'_> {
if idx >= 0 {
s.chars()
.nth(idx as usize)
.map(|ch| (ch.into_dynamic(), false))
.map(|ch| (ch.into_dynamic(), VariableType::String))
.ok_or_else(|| EvalAltResult::ErrorStringBounds(s.chars().count(), idx, pos))
} else {
Err(EvalAltResult::ErrorStringBounds(
@ -281,22 +306,28 @@ impl Engine<'_> {
fn eval_index_expr(
&mut self,
scope: &mut Scope,
id: &str,
idx: &Expr,
begin: Position,
) -> Result<(bool, usize, usize, Dynamic), EvalAltResult> {
lhs: &Expr,
idx_expr: &Expr,
) -> Result<(VariableType, Option<(String, usize)>, usize, Dynamic), EvalAltResult> {
let idx = *self
.eval_expr(scope, idx)?
.eval_expr(scope, idx_expr)?
.downcast::<i64>()
.map_err(|_| EvalAltResult::ErrorIndexExpr(idx.position()))?;
.map_err(|_| EvalAltResult::ErrorIndexExpr(idx_expr.position()))?;
Self::search_scope(
scope,
id,
|val| Self::get_indexed_value(val, idx, begin),
begin,
)
.map(|(idx_sc, (val, is_array))| (is_array, idx_sc, idx as usize, val))
match lhs {
Expr::Identifier(id, _) => Self::search_scope(
scope,
&id,
|val| Self::get_indexed_value(val, idx, lhs.position()),
lhs.position(),
)
.map(|(src_idx, (val, source_type))| {
(source_type, Some((id.clone(), src_idx)), idx as usize, val)
}),
expr => Self::get_indexed_value(self.eval_expr(scope, expr)?, idx, lhs.position())
.map(|(val, _)| (VariableType::Expression, None, idx as usize, val)),
}
}
fn str_replace_char(s: &mut String, idx: usize, new_ch: char) {
@ -333,22 +364,37 @@ impl Engine<'_> {
value
}
Expr::Index(id, idx_expr, pos) => {
let (is_array, sc_idx, idx, mut target) =
self.eval_index_expr(scope, id, idx_expr, *pos)?;
Expr::Index(lhs, idx_expr) => {
let (source_type, src, idx, mut target) =
self.eval_index_expr(scope, lhs, idx_expr)?;
let value = self.get_dot_val_helper(scope, target.as_mut(), dot_rhs);
// In case the expression mutated `target`, we need to reassign it because
// of the above `clone`.
if is_array {
scope.get_mut(id, sc_idx).downcast_mut::<Array>().unwrap()[idx] = target;
} else {
Self::str_replace_char(
scope.get_mut(id, sc_idx).downcast_mut::<String>().unwrap(), // Root is a string
idx,
*target.downcast::<char>().unwrap(), // Target should be a char
);
match source_type {
VariableType::Array => {
let src = src.unwrap();
scope
.get_mut(&src.0, src.1)
.downcast_mut::<Array>()
.unwrap()[idx] = target
}
VariableType::String => {
let src = src.unwrap();
Self::str_replace_char(
scope
.get_mut(&src.0, src.1)
.downcast_mut::<String>()
.unwrap(), // Root is a string
idx,
*target.downcast::<char>().unwrap(), // Target should be a char
)
}
_ => panic!("source_type must be either Array or String"),
}
value
@ -417,21 +463,38 @@ impl Engine<'_> {
value
}
Expr::Index(id, iex_expr, pos) => {
let (is_array, sc_idx, idx, mut target) =
self.eval_index_expr(scope, id, iex_expr, *pos)?;
Expr::Index(lhs, idx_expr) => {
let (source_type, src, idx, mut target) =
self.eval_index_expr(scope, lhs, idx_expr)?;
let value = self.set_dot_val_helper(target.as_mut(), dot_rhs, source_val);
// In case the expression mutated `target`, we need to reassign it because
// of the above `clone`.
if is_array {
scope.get_mut(id, sc_idx).downcast_mut::<Array>().unwrap()[idx] = target;
} else {
Self::str_replace_char(
scope.get_mut(id, sc_idx).downcast_mut::<String>().unwrap(), // Root is a string
idx,
*target.downcast::<char>().unwrap(), // Target should be a char
);
match source_type {
VariableType::Array => {
let src = src.unwrap();
let val = scope
.get_mut(&src.0, src.1)
.downcast_mut::<Array>()
.unwrap();
val[idx] = target
}
VariableType::String => {
let src = src.unwrap();
Self::str_replace_char(
scope
.get_mut(&src.0, src.1)
.downcast_mut::<String>()
.unwrap(), // Root is a string
idx,
*target.downcast::<char>().unwrap(), // Target should be a char
)
}
_ => panic!("source_type must be either Array or String"),
}
value
@ -447,20 +510,17 @@ impl Engine<'_> {
Expr::FloatConstant(i, _) => Ok((*i).into_dynamic()),
Expr::StringConstant(s, _) => Ok(s.into_dynamic()),
Expr::CharConstant(c, _) => Ok((*c).into_dynamic()),
Expr::Identifier(id, pos) => scope
.get(id)
.map(|(_, _, val)| val)
.ok_or_else(|| EvalAltResult::ErrorVariableNotFound(id.clone(), *pos)),
Expr::Index(id, idx_expr, pos) => self
.eval_index_expr(scope, id, idx_expr, *pos)
Expr::Identifier(id, pos) => {
Self::search_scope(scope, id, Ok, *pos).map(|(_, val)| val)
}
Expr::Index(lhs, idx_expr) => self
.eval_index_expr(scope, lhs, idx_expr)
.map(|(_, _, _, x)| x),
Expr::Assignment(ref id, rhs) => {
Expr::Assignment(lhs, rhs) => {
let rhs_val = self.eval_expr(scope, rhs)?;
match id.as_ref() {
match lhs.as_ref() {
Expr::Identifier(name, pos) => {
if let Some((idx, _, _)) = scope.get(name) {
*scope.get_mut(name, idx) = rhs_val;
@ -469,47 +529,44 @@ impl Engine<'_> {
Err(EvalAltResult::ErrorVariableNotFound(name.clone(), *pos))
}
}
Expr::Index(id, idx_expr, pos) => {
let idx_pos = idx_expr.position();
let idx = *match self.eval_expr(scope, &idx_expr)?.downcast::<i64>() {
Ok(x) => x,
_ => return Err(EvalAltResult::ErrorIndexExpr(idx_pos)),
};
Expr::Index(idx_lhs, idx_expr) => {
let (source_type, src, idx, _) =
self.eval_index_expr(scope, idx_lhs, idx_expr)?;
let val = match scope.get(id) {
Some((idx, _, _)) => scope.get_mut(id, idx),
_ => {
return Err(EvalAltResult::ErrorVariableNotFound(id.clone(), *pos))
match source_type {
VariableType::Array => {
let src = src.unwrap();
scope
.get_mut(&src.0, src.1)
.downcast_mut::<Array>()
.map(|arr| (arr[idx as usize] = rhs_val).into_dynamic())
.ok_or_else(|| {
EvalAltResult::ErrorIndexExpr(idx_lhs.position())
})
}
};
if let Some(arr) = val.downcast_mut() as Option<&mut Array> {
if idx < 0 {
Err(EvalAltResult::ErrorArrayBounds(arr.len(), idx, idx_pos))
} else if idx as usize >= arr.len() {
Err(EvalAltResult::ErrorArrayBounds(arr.len(), idx, idx_pos))
} else {
arr[idx as usize] = rhs_val;
Ok(().into_dynamic())
VariableType::String => {
let src = src.unwrap();
scope
.get_mut(&src.0, src.1)
.downcast_mut::<String>()
.map(|s| {
Self::str_replace_char(
s,
idx as usize,
*rhs_val.downcast::<char>().unwrap(),
)
.into_dynamic()
})
.ok_or_else(|| {
EvalAltResult::ErrorIndexExpr(idx_lhs.position())
})
}
} else if let Some(s) = val.downcast_mut() as Option<&mut String> {
let s_len = s.chars().count();
if idx < 0 {
Err(EvalAltResult::ErrorStringBounds(s_len, idx, idx_pos))
} else if idx as usize >= s_len {
Err(EvalAltResult::ErrorStringBounds(s_len, idx, idx_pos))
} else {
Self::str_replace_char(
s,
idx as usize,
*rhs_val.downcast::<char>().unwrap(),
);
Ok(().into_dynamic())
}
} else {
Err(EvalAltResult::ErrorIndexExpr(idx_pos))
_ => Err(EvalAltResult::ErrorAssignmentToUnknownLHS(
idx_lhs.position(),
)),
}
}
@ -517,7 +574,7 @@ impl Engine<'_> {
self.set_dot_val(scope, dot_lhs, dot_rhs, rhs_val)
}
_ => Err(EvalAltResult::ErrorAssignmentToUnknownLHS(id.position())),
_ => Err(EvalAltResult::ErrorAssignmentToUnknownLHS(lhs.position())),
}
}

60
src/parser.rs
View File

@ -132,7 +132,7 @@ pub enum Expr {
FunctionCall(String, Vec<Expr>, Option<Dynamic>, Position),
Assignment(Box<Expr>, Box<Expr>),
Dot(Box<Expr>, Box<Expr>),
Index(String, Box<Expr>, Position),
Index(Box<Expr>, Box<Expr>),
Array(Vec<Expr>, Position),
And(Box<Expr>, Box<Expr>),
Or(Box<Expr>, Box<Expr>),
@ -150,15 +150,16 @@ impl Expr {
| Expr::CharConstant(_, pos)
| Expr::StringConstant(_, pos)
| Expr::FunctionCall(_, _, _, pos)
| Expr::Index(_, _, pos)
| Expr::Array(_, pos)
| Expr::True(pos)
| Expr::False(pos)
| Expr::Unit(pos) => *pos,
Expr::Assignment(e, _) | Expr::Dot(e, _) | Expr::And(e, _) | Expr::Or(e, _) => {
e.position()
}
Expr::Index(e, _)
| Expr::Assignment(e, _)
| Expr::Dot(e, _)
| Expr::And(e, _)
| Expr::Or(e, _) => e.position(),
}
}
}
@ -1076,15 +1077,14 @@ fn parse_call_expr<'a>(
}
fn parse_index_expr<'a>(
id: String,
lhs: Box<Expr>,
input: &mut Peekable<TokenIterator<'a>>,
begin: Position,
) -> Result<Expr, ParseError> {
match parse_expr(input) {
Ok(idx) => match input.peek() {
Ok(idx_expr) => match input.peek() {
Some(&(Token::RightBracket, _)) => {
input.next();
return Ok(Expr::Index(id, Box::new(idx), begin));
return Ok(Expr::Index(lhs, Box::new(idx_expr)));
}
Some(&(_, pos)) => return Err(ParseError::new(PERR::MalformedIndexExpr, pos)),
None => return Err(ParseError::new(PERR::MalformedIndexExpr, Position::eof())),
@ -1105,7 +1105,7 @@ fn parse_ident_expr<'a>(
}
Some(&(Token::LeftBracket, _)) => {
input.next();
parse_index_expr(id, input, begin)
parse_index_expr(Box::new(Expr::Identifier(id, begin)), input)
}
Some(_) => Ok(Expr::Identifier(id, begin)),
None => Ok(Expr::Identifier(id, Position::eof())),
@ -1147,14 +1147,30 @@ fn parse_array_expr<'a>(
}
fn parse_primary<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Expr, ParseError> {
match input.next() {
let token = input.next();
let mut follow_on = false;
let r = match token {
Some((Token::IntegerConstant(x), pos)) => Ok(Expr::IntegerConstant(x, pos)),
Some((Token::FloatConstant(x), pos)) => Ok(Expr::FloatConstant(x, pos)),
Some((Token::StringConst(s), pos)) => Ok(Expr::StringConstant(s, pos)),
Some((Token::CharConstant(c), pos)) => Ok(Expr::CharConstant(c, pos)),
Some((Token::Identifier(s), pos)) => parse_ident_expr(s, input, pos),
Some((Token::LeftParen, pos)) => parse_paren_expr(input, pos),
Some((Token::LeftBracket, pos)) => parse_array_expr(input, pos),
Some((Token::StringConst(s), pos)) => {
follow_on = true;
Ok(Expr::StringConstant(s, pos))
}
Some((Token::Identifier(s), pos)) => {
follow_on = true;
parse_ident_expr(s, input, pos)
}
Some((Token::LeftParen, pos)) => {
follow_on = true;
parse_paren_expr(input, pos)
}
Some((Token::LeftBracket, pos)) => {
follow_on = true;
parse_array_expr(input, pos)
}
Some((Token::True, pos)) => Ok(Expr::True(pos)),
Some((Token::False, pos)) => Ok(Expr::False(pos)),
Some((Token::LexError(le), pos)) => {
@ -1165,6 +1181,20 @@ fn parse_primary<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Expr, Pa
pos,
)),
None => Err(ParseError::new(PERR::InputPastEndOfFile, Position::eof())),
}?;
if !follow_on {
return Ok(r);
}
// Post processing
match input.peek() {
Some(&(Token::LeftBracket, _)) => {
// Possible indexing
input.next();
parse_index_expr(Box::new(r), input)
}
_ => Ok(r),
}
}

20
src/result.rs
View File

@ -132,16 +132,24 @@ impl std::fmt::Display for EvalAltResult {
write!(f, "{}: {} < 0 ({})", desc, index, pos)
}
Self::ErrorArrayBounds(max, _, pos) if *max == 0 => write!(f, "{} ({})", desc, pos),
Self::ErrorArrayBounds(max, index, pos) => {
write!(f, "{} (max {}): {} ({})", desc, max - 1, index, pos)
}
Self::ErrorArrayBounds(max, index, pos) => write!(
f,
"Array index {} is out of bounds: max {} elements ({})",
index,
max - 1,
pos
),
Self::ErrorStringBounds(_, index, pos) if *index < 0 => {
write!(f, "{}: {} < 0 ({})", desc, index, pos)
}
Self::ErrorStringBounds(max, _, pos) if *max == 0 => write!(f, "{} ({})", desc, pos),
Self::ErrorStringBounds(max, index, pos) => {
write!(f, "{} (max {}): {} ({})", desc, max - 1, index, pos)
}
Self::ErrorStringBounds(max, index, pos) => write!(
f,
"String index {} is out of bounds: max {} characters ({})",
index,
max - 1,
pos
),
}
}
}