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Mandatory semiclolons separating statements.

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This commit is contained in:
Stephen Chung 2020-03-17 14:29:22 +08:00
parent c3d4a1b5e9
commit b26ca753c2
3 changed files with 84 additions and 21 deletions
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9
src/error.rs
View File

@ -60,6 +60,8 @@ pub enum ParseErrorType {
MissingRightBracket(String),
/// A list of expressions is missing the separating ','.
MissingComma(String),
/// A statement is missing the ending ';'.
MissingSemicolon(String),
/// An expression in function call arguments `()` has syntax error.
MalformedCallExpr(String),
/// An expression in indexing brackets `[]` has syntax error.
@ -119,6 +121,7 @@ impl ParseError {
#[cfg(not(feature = "no_index"))]
ParseErrorType::MissingRightBracket(_) => "Expecting ']'",
ParseErrorType::MissingComma(_) => "Expecting ','",
ParseErrorType::MissingSemicolon(_) => "Expecting ';'",
ParseErrorType::MalformedCallExpr(_) => "Invalid expression in function call arguments",
#[cfg(not(feature = "no_index"))]
ParseErrorType::MalformedIndexExpr(_) => "Invalid index in indexing expression",
@ -130,7 +133,7 @@ impl ParseError {
#[cfg(not(feature = "no_function"))]
ParseErrorType::FnMissingParams(_) => "Expecting parameters in function declaration",
#[cfg(not(feature = "no_function"))]
ParseErrorType::WrongFnDefinition => "Function definitions must be at top level and cannot be inside a block or another function",
ParseErrorType::WrongFnDefinition => "Function definitions must be at global level and cannot be inside a block or another function",
ParseErrorType::AssignmentToInvalidLHS => "Cannot assign to this expression",
ParseErrorType::AssignmentToCopy => "Cannot assign to this expression because it will only be changing a copy of the value",
ParseErrorType::AssignmentToConstant(_) => "Cannot assign to a constant variable."
@ -168,7 +171,9 @@ impl fmt::Display for ParseError {
#[cfg(not(feature = "no_index"))]
ParseErrorType::MissingRightBracket(ref s) => write!(f, "{} for {}", self.desc(), s)?,
ParseErrorType::MissingComma(ref s) => write!(f, "{} for {}", self.desc(), s)?,
ParseErrorType::MissingSemicolon(ref s) | ParseErrorType::MissingComma(ref s) => {
write!(f, "{} for {}", self.desc(), s)?
}
ParseErrorType::AssignmentToConstant(ref s) if s.is_empty() => {
write!(f, "{}", self.desc())?

4
src/optimize.rs
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@ -455,7 +455,7 @@ pub(crate) fn optimize<'a>(
if let Stmt::Const(name, value, _) = &stmt {
// Load constants
state.push_constant(name, value.as_ref().clone());
stmt // Keep it in the top scope
stmt // Keep it in the global scope
} else {
// Keep all variable declarations at this level
// and always keep the last return value
@ -474,7 +474,7 @@ pub(crate) fn optimize<'a>(
// Eliminate code that is pure but always keep the last statement
let last_stmt = result.pop();
// Remove all pure statements at top level
// Remove all pure statements at global level
result.retain(|stmt| !matches!(stmt, Stmt::Expr(expr) if expr.is_pure()));
if let Some(stmt) = last_stmt {

92
src/parser.rs
View File

@ -213,6 +213,23 @@ impl Stmt {
matches!(self, Stmt::Let(_, _, _))
}
pub fn is_self_terminated(&self) -> bool {
match self {
Stmt::Noop(_)
| Stmt::IfElse(_, _, _)
| Stmt::While(_, _)
| Stmt::Loop(_)
| Stmt::For(_, _, _)
| Stmt::Block(_, _) => true,
Stmt::Let(_, _, _)
| Stmt::Const(_, _, _)
| Stmt::Expr(_)
| Stmt::Break(_)
| Stmt::ReturnWithVal(_, _, _) => false,
}
}
pub fn position(&self) -> Position {
match self {
Stmt::Noop(pos)
@ -1923,22 +1940,42 @@ fn parse_block<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Stmt, Pars
})? {
(Token::RightBrace, _) => (), // empty block
#[cfg(not(feature = "no_function"))]
(Token::Fn, pos) => return Err(ParseError::new(PERR::WrongFnDefinition, *pos)),
_ => {
while input.peek().is_some() {
// Parse statements inside the block
statements.push(parse_stmt(input)?);
let stmt = parse_stmt(input)?;
// Notice semicolons are optional
if let Some((Token::SemiColon, _)) = input.peek() {
input.next();
}
// See if it needs a terminating semicolon
let need_semicolon = !stmt.is_self_terminated();
statements.push(stmt);
// End block with right brace
if let Some((Token::RightBrace, _)) = input.peek() {
break;
}
match input.peek() {
Some((Token::SemiColon, _)) => {
input.next();
}
Some((_, _)) if !need_semicolon => (),
Some((_, pos)) => {
// Semicolons are not optional between statements
return Err(ParseError::new(
PERR::MissingSemicolon("terminating a statement".into()),
*pos,
));
}
None => {
return Err(ParseError::new(
PERR::MissingRightBrace("end of block".into()),
Position::eof(),
))
}
}
}
}
}
@ -1969,6 +2006,9 @@ fn parse_stmt<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Stmt, Parse
.peek()
.ok_or_else(|| ParseError::new(PERR::InputPastEndOfFile, Position::eof()))?
{
#[cfg(not(feature = "no_function"))]
(Token::Fn, pos) => return Err(ParseError::new(PERR::WrongFnDefinition, *pos)),
(Token::If, _) => parse_if(input),
(Token::While, _) => parse_while(input),
(Token::Loop, _) => parse_loop(input),
@ -2107,16 +2147,16 @@ fn parse_fn<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<FnDef, ParseE
})
}
fn parse_top_level<'a, 'e>(
fn parse_global_level<'a, 'e>(
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() {
match input.peek().expect("should not be None") {
#[cfg(not(feature = "no_function"))]
(Token::Fn, _) => {
#[cfg(not(feature = "no_function"))]
{
if matches!(input.peek().expect("should not be None"), (Token::Fn, _)) {
let f = parse_fn(input)?;
// Ensure list is sorted
@ -2124,13 +2164,31 @@ fn parse_top_level<'a, 'e>(
Ok(n) => functions[n] = f, // Override previous definition
Err(n) => functions.insert(n, f), // New function definition
}
continue;
}
_ => statements.push(parse_stmt(input)?),
}
// Notice semicolons are optional
if let Some((Token::SemiColon, _)) = input.peek() {
input.next();
let stmt = parse_stmt(input)?;
let need_semicolon = !stmt.is_self_terminated();
statements.push(stmt);
match input.peek() {
None => break,
Some((Token::SemiColon, _)) => {
input.next();
}
Some((_, _)) if !need_semicolon => (),
Some((_, pos)) => {
// Semicolons are not optional between statements
return Err(ParseError::new(
PERR::MissingSemicolon("terminating a statement".into()),
*pos,
));
}
}
}
@ -2142,7 +2200,7 @@ pub fn parse<'a, 'e>(
engine: &Engine<'e>,
scope: &Scope,
) -> Result<AST, ParseError> {
let (statements, functions) = parse_top_level(input)?;
let (statements, functions) = parse_global_level(input)?;
Ok(
#[cfg(not(feature = "no_optimize"))]