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Disable if-expression when parsing expressions.

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This commit is contained in:
Stephen Chung 2020-06-01 13:26:20 +08:00
parent 3f9d0895de
commit b8b12055b9
2 changed files with 117 additions and 76 deletions
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186
src/parser.rs
View File

@ -700,7 +700,8 @@ fn parse_paren_expr<'a>(
state: &mut ParseState,
pos: Position,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Expr, ParseError> {
if level > state.max_expr_depth {
return Err(PERR::ExprTooDeep.into_err(pos));
@ -710,7 +711,7 @@ fn parse_paren_expr<'a>(
return Ok(Expr::Unit(pos));
}
let expr = parse_expr(input, state, level + 1, allow_stmt_expr)?;
let expr = parse_expr(input, state, level + 1, if_expr, stmt_expr)?;
match input.next().unwrap() {
// ( xxx )
@ -734,7 +735,8 @@ fn parse_call_expr<'a>(
mut modules: Option<Box<ModuleRef>>,
begin: Position,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Expr, ParseError> {
let (token, pos) = input.peek().unwrap();
@ -788,7 +790,7 @@ fn parse_call_expr<'a>(
}
loop {
args.push(parse_expr(input, state, level + 1, allow_stmt_expr)?);
args.push(parse_expr(input, state, level + 1, if_expr, stmt_expr)?);
match input.peek().unwrap() {
// id(...args)
@ -855,13 +857,14 @@ fn parse_index_chain<'a>(
lhs: Expr,
pos: Position,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Expr, ParseError> {
if level > state.max_expr_depth {
return Err(PERR::ExprTooDeep.into_err(pos));
}
let idx_expr = parse_expr(input, state, level + 1, allow_stmt_expr)?;
let idx_expr = parse_expr(input, state, level + 1, if_expr, stmt_expr)?;
// Check type of indexing - must be integer or string
match &idx_expr {
@ -1008,7 +1011,8 @@ fn parse_index_chain<'a>(
idx_expr,
idx_pos,
level + 1,
allow_stmt_expr,
if_expr,
stmt_expr,
)?;
// Indexing binds to right
Ok(Expr::Index(Box::new((lhs, idx_expr, pos))))
@ -1042,7 +1046,8 @@ fn parse_array_literal<'a>(
state: &mut ParseState,
pos: Position,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Expr, ParseError> {
if level > state.max_expr_depth {
return Err(PERR::ExprTooDeep.into_err(pos));
@ -1052,7 +1057,8 @@ fn parse_array_literal<'a>(
if !match_token(input, Token::RightBracket)? {
while !input.peek().unwrap().0.is_eof() {
arr.push(parse_expr(input, state, level + 1, allow_stmt_expr)?);
let expr = parse_expr(input, state, level + 1, if_expr, stmt_expr)?;
arr.push(expr);
match input.peek().unwrap() {
(Token::Comma, _) => eat_token(input, Token::Comma),
@ -1090,7 +1096,8 @@ fn parse_map_literal<'a>(
state: &mut ParseState,
pos: Position,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Expr, ParseError> {
if level > state.max_expr_depth {
return Err(PERR::ExprTooDeep.into_err(pos));
@ -1140,7 +1147,7 @@ fn parse_map_literal<'a>(
}
};
let expr = parse_expr(input, state, level + 1, allow_stmt_expr)?;
let expr = parse_expr(input, state, level + 1, if_expr, stmt_expr)?;
map.push(((name, pos), expr));
@ -1191,7 +1198,8 @@ fn parse_primary<'a>(
input: &mut Peekable<TokenIterator<'a>>,
state: &mut ParseState,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Expr, ParseError> {
let (token, pos) = input.peek().unwrap();
let pos = *pos;
@ -1202,8 +1210,8 @@ fn parse_primary<'a>(
let (token, _) = match token {
// { - block statement as expression
Token::LeftBrace if allow_stmt_expr => {
return parse_block(input, state, false, level + 1, allow_stmt_expr)
Token::LeftBrace if stmt_expr => {
return parse_block(input, state, false, level + 1, if_expr, stmt_expr)
.map(|block| Expr::Stmt(Box::new((block, pos))));
}
Token::EOF => return Err(PERR::UnexpectedEOF.into_err(pos)),
@ -1220,11 +1228,13 @@ fn parse_primary<'a>(
let index = state.find(&s);
Expr::Variable(Box::new(((s, pos), None, 0, index)))
}
Token::LeftParen => parse_paren_expr(input, state, pos, level + 1, allow_stmt_expr)?,
Token::LeftParen => parse_paren_expr(input, state, pos, level + 1, if_expr, stmt_expr)?,
#[cfg(not(feature = "no_index"))]
Token::LeftBracket => parse_array_literal(input, state, pos, level + 1, allow_stmt_expr)?,
Token::LeftBracket => {
parse_array_literal(input, state, pos, level + 1, if_expr, stmt_expr)?
}
#[cfg(not(feature = "no_object"))]
Token::MapStart => parse_map_literal(input, state, pos, level + 1, allow_stmt_expr)?,
Token::MapStart => parse_map_literal(input, state, pos, level + 1, if_expr, stmt_expr)?,
Token::True => Expr::True(pos),
Token::False => Expr::False(pos),
Token::LexError(err) => return Err(PERR::BadInput(err.to_string()).into_err(pos)),
@ -1247,7 +1257,16 @@ fn parse_primary<'a>(
// Function call
(Expr::Variable(x), Token::LeftParen) => {
let ((name, pos), modules, _, _) = *x;
parse_call_expr(input, state, name, modules, pos, level + 1, allow_stmt_expr)?
parse_call_expr(
input,
state,
name,
modules,
pos,
level + 1,
if_expr,
stmt_expr,
)?
}
(Expr::Property(_), _) => unreachable!(),
// module access
@ -1269,7 +1288,7 @@ fn parse_primary<'a>(
// Indexing
#[cfg(not(feature = "no_index"))]
(expr, Token::LeftBracket) => {
parse_index_chain(input, state, expr, token_pos, level + 1, allow_stmt_expr)?
parse_index_chain(input, state, expr, token_pos, level + 1, if_expr, stmt_expr)?
}
// Unknown postfix operator
(expr, token) => panic!(
@ -1301,7 +1320,8 @@ fn parse_unary<'a>(
input: &mut Peekable<TokenIterator<'a>>,
state: &mut ParseState,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Expr, ParseError> {
let (token, pos) = input.peek().unwrap();
let pos = *pos;
@ -1312,15 +1332,15 @@ fn parse_unary<'a>(
match token {
// If statement is allowed to act as expressions
Token::If => Ok(Expr::Stmt(Box::new((
parse_if(input, state, false, level + 1, allow_stmt_expr)?,
Token::If if if_expr => Ok(Expr::Stmt(Box::new((
parse_if(input, state, false, level + 1, if_expr, stmt_expr)?,
pos,
)))),
// -expr
Token::UnaryMinus => {
let pos = eat_token(input, Token::UnaryMinus);
match parse_unary(input, state, level + 1, allow_stmt_expr)? {
match parse_unary(input, state, level + 1, if_expr, stmt_expr)? {
// Negative integer
Expr::IntegerConstant(x) => {
let (num, pos) = *x;
@ -1369,13 +1389,14 @@ fn parse_unary<'a>(
// +expr
Token::UnaryPlus => {
eat_token(input, Token::UnaryPlus);
parse_unary(input, state, level + 1, allow_stmt_expr)
parse_unary(input, state, level + 1, if_expr, stmt_expr)
}
// !expr
Token::Bang => {
let pos = eat_token(input, Token::Bang);
let mut args = StaticVec::new();
args.push(parse_primary(input, state, level + 1, allow_stmt_expr)?);
let expr = parse_primary(input, state, level + 1, if_expr, stmt_expr)?;
args.push(expr);
let op = "!";
let hash = calc_fn_hash(empty(), op, 2, empty());
@ -1391,7 +1412,7 @@ fn parse_unary<'a>(
// <EOF>
Token::EOF => Err(PERR::UnexpectedEOF.into_err(pos)),
// All other tokens
_ => parse_primary(input, state, level + 1, allow_stmt_expr),
_ => parse_primary(input, state, level + 1, if_expr, stmt_expr),
}
}
@ -1451,7 +1472,8 @@ fn parse_op_assignment_stmt<'a>(
state: &mut ParseState,
lhs: Expr,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Expr, ParseError> {
let (token, pos) = input.peek().unwrap();
let pos = *pos;
@ -1479,7 +1501,7 @@ fn parse_op_assignment_stmt<'a>(
};
let (_, pos) = input.next().unwrap();
let rhs = parse_expr(input, state, level + 1, allow_stmt_expr)?;
let rhs = parse_expr(input, state, level + 1, if_expr, stmt_expr)?;
make_assignment_stmt(op, state, lhs, rhs, pos)
}
@ -1694,7 +1716,8 @@ fn parse_binary_op<'a>(
parent_precedence: u8,
lhs: Expr,
mut level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Expr, ParseError> {
if level > state.max_expr_depth {
return Err(PERR::ExprTooDeep.into_err(lhs.position()));
@ -1715,14 +1738,14 @@ fn parse_binary_op<'a>(
let (op_token, pos) = input.next().unwrap();
let rhs = parse_unary(input, state, level, allow_stmt_expr)?;
let rhs = parse_unary(input, state, level, if_expr, stmt_expr)?;
let next_precedence = input.peek().unwrap().0.precedence();
// 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, level, allow_stmt_expr)?
parse_binary_op(input, state, precedence, rhs, level, if_expr, stmt_expr)?
} else {
// Otherwise bind to left (even if next operator has the same precedence)
rhs
@ -1810,7 +1833,8 @@ fn parse_expr<'a>(
input: &mut Peekable<TokenIterator<'a>>,
state: &mut ParseState,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Expr, ParseError> {
let (_, pos) = input.peek().unwrap();
@ -1818,8 +1842,8 @@ fn parse_expr<'a>(
return Err(PERR::ExprTooDeep.into_err(*pos));
}
let lhs = parse_unary(input, state, level + 1, allow_stmt_expr)?;
parse_binary_op(input, state, 1, lhs, level + 1, allow_stmt_expr)
let lhs = parse_unary(input, state, level + 1, if_expr, stmt_expr)?;
parse_binary_op(input, state, 1, lhs, level + 1, if_expr, stmt_expr)
}
/// Make sure that the expression is not a statement expression (i.e. wrapped in `{}`).
@ -1870,7 +1894,8 @@ fn parse_if<'a>(
state: &mut ParseState,
breakable: bool,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Stmt, ParseError> {
// if ...
let pos = eat_token(input, Token::If);
@ -1881,18 +1906,18 @@ fn parse_if<'a>(
// if guard { if_body }
ensure_not_statement_expr(input, "a boolean")?;
let guard = parse_expr(input, state, level + 1, allow_stmt_expr)?;
let guard = parse_expr(input, state, level + 1, if_expr, stmt_expr)?;
ensure_not_assignment(input)?;
let if_body = parse_block(input, state, breakable, level + 1, allow_stmt_expr)?;
let if_body = parse_block(input, state, breakable, level + 1, if_expr, stmt_expr)?;
// 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, breakable, level + 1, allow_stmt_expr)?
parse_if(input, state, breakable, level + 1, if_expr, stmt_expr)?
} else {
// if guard { if_body } else { else-body }
parse_block(input, state, breakable, level + 1, allow_stmt_expr)?
parse_block(input, state, breakable, level + 1, if_expr, stmt_expr)?
})
} else {
None
@ -1906,7 +1931,8 @@ fn parse_while<'a>(
input: &mut Peekable<TokenIterator<'a>>,
state: &mut ParseState,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Stmt, ParseError> {
// while ...
let pos = eat_token(input, Token::While);
@ -1917,9 +1943,9 @@ fn parse_while<'a>(
// while guard { body }
ensure_not_statement_expr(input, "a boolean")?;
let guard = parse_expr(input, state, level + 1, allow_stmt_expr)?;
let guard = parse_expr(input, state, level + 1, if_expr, stmt_expr)?;
ensure_not_assignment(input)?;
let body = parse_block(input, state, true, level + 1, allow_stmt_expr)?;
let body = parse_block(input, state, true, level + 1, if_expr, stmt_expr)?;
Ok(Stmt::While(Box::new((guard, body))))
}
@ -1929,7 +1955,8 @@ fn parse_loop<'a>(
input: &mut Peekable<TokenIterator<'a>>,
state: &mut ParseState,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Stmt, ParseError> {
// loop ...
let pos = eat_token(input, Token::Loop);
@ -1939,7 +1966,7 @@ fn parse_loop<'a>(
}
// loop { body }
let body = parse_block(input, state, true, level + 1, allow_stmt_expr)?;
let body = parse_block(input, state, true, level + 1, if_expr, stmt_expr)?;
Ok(Stmt::Loop(Box::new(body)))
}
@ -1949,7 +1976,8 @@ fn parse_for<'a>(
input: &mut Peekable<TokenIterator<'a>>,
state: &mut ParseState,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Stmt, ParseError> {
// for ...
let pos = eat_token(input, Token::For);
@ -1984,12 +2012,12 @@ fn parse_for<'a>(
// for name in expr { body }
ensure_not_statement_expr(input, "a boolean")?;
let expr = parse_expr(input, state, level + 1, allow_stmt_expr)?;
let expr = parse_expr(input, state, level + 1, if_expr, stmt_expr)?;
let prev_len = state.len();
state.push((name.clone(), ScopeEntryType::Normal));
let body = parse_block(input, state, true, level + 1, allow_stmt_expr)?;
let body = parse_block(input, state, true, level + 1, if_expr, stmt_expr)?;
state.truncate(prev_len);
@ -2002,7 +2030,8 @@ fn parse_let<'a>(
state: &mut ParseState,
var_type: ScopeEntryType,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Stmt, ParseError> {
// let/const... (specified in `var_type`)
let (_, pos) = input.next().unwrap();
@ -2021,7 +2050,7 @@ fn parse_let<'a>(
// let name = ...
if match_token(input, Token::Equals)? {
// let name = expr
let init_value = parse_expr(input, state, level + 1, allow_stmt_expr)?;
let init_value = parse_expr(input, state, level + 1, if_expr, stmt_expr)?;
match var_type {
// let name = expr
@ -2063,7 +2092,8 @@ fn parse_import<'a>(
input: &mut Peekable<TokenIterator<'a>>,
state: &mut ParseState,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Stmt, ParseError> {
// import ...
let pos = eat_token(input, Token::Import);
@ -2073,7 +2103,7 @@ fn parse_import<'a>(
}
// import expr ...
let expr = parse_expr(input, state, level + 1, allow_stmt_expr)?;
let expr = parse_expr(input, state, level + 1, if_expr, stmt_expr)?;
// import expr as ...
match input.next().unwrap() {
@ -2169,7 +2199,8 @@ fn parse_block<'a>(
state: &mut ParseState,
breakable: bool,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Stmt, ParseError> {
// Must start with {
let pos = match input.next().unwrap() {
@ -2193,7 +2224,15 @@ fn parse_block<'a>(
while !match_token(input, Token::RightBrace)? {
// Parse statements inside the block
let stmt = parse_stmt(input, state, breakable, false, level + 1, allow_stmt_expr)?;
let stmt = parse_stmt(
input,
state,
breakable,
false,
level + 1,
if_expr,
stmt_expr,
)?;
// See if it needs a terminating semicolon
let need_semicolon = !stmt.is_self_terminated();
@ -2240,7 +2279,8 @@ fn parse_expr_stmt<'a>(
input: &mut Peekable<TokenIterator<'a>>,
state: &mut ParseState,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Stmt, ParseError> {
let (_, pos) = input.peek().unwrap();
@ -2248,8 +2288,8 @@ fn parse_expr_stmt<'a>(
return Err(PERR::ExprTooDeep.into_err(*pos));
}
let expr = parse_expr(input, state, level + 1, allow_stmt_expr)?;
let expr = parse_op_assignment_stmt(input, state, expr, level + 1, allow_stmt_expr)?;
let expr = parse_expr(input, state, level + 1, if_expr, stmt_expr)?;
let expr = parse_op_assignment_stmt(input, state, expr, level + 1, if_expr, stmt_expr)?;
Ok(Stmt::Expr(Box::new(expr)))
}
@ -2260,7 +2300,8 @@ fn parse_stmt<'a>(
breakable: bool,
is_global: bool,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<Stmt, ParseError> {
use ScopeEntryType::{Constant, Normal};
@ -2277,7 +2318,7 @@ fn parse_stmt<'a>(
// Semicolon - empty statement
Token::SemiColon => Ok(Stmt::Noop(*pos)),
Token::LeftBrace => parse_block(input, state, breakable, level + 1, allow_stmt_expr),
Token::LeftBrace => parse_block(input, state, breakable, level + 1, if_expr, stmt_expr),
// fn ...
#[cfg(not(feature = "no_function"))]
@ -2285,10 +2326,10 @@ fn parse_stmt<'a>(
#[cfg(not(feature = "no_function"))]
Token::Fn => unreachable!(),
Token::If => parse_if(input, state, breakable, level + 1, allow_stmt_expr),
Token::While => parse_while(input, state, level + 1, allow_stmt_expr),
Token::Loop => parse_loop(input, state, level + 1, allow_stmt_expr),
Token::For => parse_for(input, state, level + 1, allow_stmt_expr),
Token::If => parse_if(input, state, breakable, level + 1, if_expr, stmt_expr),
Token::While => parse_while(input, state, level + 1, if_expr, stmt_expr),
Token::Loop => parse_loop(input, state, level + 1, if_expr, stmt_expr),
Token::For => parse_for(input, state, level + 1, if_expr, stmt_expr),
Token::Continue if breakable => {
let pos = eat_token(input, Token::Continue);
@ -2318,7 +2359,7 @@ fn parse_stmt<'a>(
}
// `return` or `throw` with expression
(_, _) => {
let expr = parse_expr(input, state, level + 1, allow_stmt_expr)?;
let expr = parse_expr(input, state, level + 1, if_expr, stmt_expr)?;
let pos = expr.position();
Ok(Stmt::ReturnWithVal(Box::new((
@ -2329,9 +2370,9 @@ fn parse_stmt<'a>(
}
}
Token::Let => parse_let(input, state, Normal, level + 1, allow_stmt_expr),
Token::Const => parse_let(input, state, Constant, level + 1, allow_stmt_expr),
Token::Import => parse_import(input, state, level + 1, allow_stmt_expr),
Token::Let => parse_let(input, state, Normal, level + 1, if_expr, stmt_expr),
Token::Const => parse_let(input, state, Constant, level + 1, if_expr, stmt_expr),
Token::Import => parse_import(input, state, level + 1, if_expr, stmt_expr),
#[cfg(not(feature = "no_module"))]
Token::Export if !is_global => Err(PERR::WrongExport.into_err(*pos)),
@ -2339,7 +2380,7 @@ fn parse_stmt<'a>(
#[cfg(not(feature = "no_module"))]
Token::Export => parse_export(input, state, level + 1),
_ => parse_expr_stmt(input, state, level + 1, allow_stmt_expr),
_ => parse_expr_stmt(input, state, level + 1, if_expr, stmt_expr),
}
}
@ -2350,7 +2391,8 @@ fn parse_fn<'a>(
state: &mut ParseState,
access: FnAccess,
level: usize,
allow_stmt_expr: bool,
if_expr: bool,
stmt_expr: bool,
) -> Result<FnDef, ParseError> {
let pos = eat_token(input, Token::Fn);
@ -2421,7 +2463,7 @@ fn parse_fn<'a>(
// Parse function body
let body = match input.peek().unwrap() {
(Token::LeftBrace, _) => parse_block(input, state, false, level + 1, allow_stmt_expr)?,
(Token::LeftBrace, _) => parse_block(input, state, false, level + 1, if_expr, stmt_expr)?,
(_, pos) => return Err(PERR::FnMissingBody(name).into_err(*pos)),
};
@ -2444,7 +2486,7 @@ pub fn parse_global_expr<'a>(
max_expr_depth: usize,
) -> Result<AST, ParseError> {
let mut state = ParseState::new(max_expr_depth);
let expr = parse_expr(input, &mut state, 0, false)?;
let expr = parse_expr(input, &mut state, 0, false, false)?;
match input.peek().unwrap() {
(Token::EOF, _) => (),
@ -2489,7 +2531,7 @@ fn parse_global_level<'a>(
#[cfg(not(feature = "no_function"))]
(Token::Fn, _) => {
let mut state = ParseState::new(max_expr_depth.1);
let func = parse_fn(input, &mut state, access, 0, true)?;
let func = parse_fn(input, &mut state, access, 0, true, true)?;
// Qualifiers (none) + function name + number of arguments.
let hash = calc_fn_hash(empty(), &func.name, func.params.len(), empty());
@ -2508,7 +2550,7 @@ fn parse_global_level<'a>(
}
}
// Actual statement
let stmt = parse_stmt(input, &mut state, false, true, 0, true)?;
let stmt = parse_stmt(input, &mut state, false, true, 0, true, true)?;
let need_semicolon = !stmt.is_self_terminated();

7
tests/expressions.rs
View File

@ -12,10 +12,9 @@ fn test_expressions() -> Result<(), Box<EvalAltResult>> {
engine.eval_expression_with_scope::<INT>(&mut scope, "2 + (x + 10) * 2")?,
42
);
assert_eq!(
engine.eval_expression_with_scope::<INT>(&mut scope, "if x > 0 { 42 } else { 123 }")?,
42
);
assert!(engine
.eval_expression_with_scope::<INT>(&mut scope, "if x > 0 { 42 } else { 123 }")
.is_err());
assert!(engine.eval_expression::<()>("40 + 2;").is_err());
assert!(engine.eval_expression::<()>("40 + { 2 }").is_err());