Parser - Parse function declarations

This commit is contained in:
Emmanuel BENOîT 2023-01-02 18:56:45 +01:00
parent 9c7445d904
commit 250eddea71

View file

@ -115,6 +115,8 @@ impl Parser {
fn parse_statement(&mut self) -> ParserResult<ast::StmtNode> {
if self.expect(&[TokenType::Var]).is_some() {
self.parse_var_declaration()
} else if self.expect(&[TokenType::Fun]).is_some() {
self.parse_fun_declaration("function")
} else if self.expect(&[TokenType::LeftBrace]).is_some() {
self.parse_block()
} else if self.expect(&[TokenType::Address]).is_some() {
@ -148,8 +150,8 @@ impl Parser {
/// Parse the following rule:
/// ```
/// declaration := "var" IDENTIFIER ";"
/// declaration := "var" IDENTIFIER "=" expression ";"
/// var_declaration := "var" IDENTIFIER ";"
/// var_declaration := "var" IDENTIFIER "=" expression ";"
/// ```
fn parse_var_declaration(&mut self) -> ParserResult<ast::StmtNode> {
let name = match self.peek().token_type {
@ -167,6 +169,68 @@ impl Parser {
Ok(ast::StmtNode::VarDecl(name, initializer))
}
/// Parse the following rule:
/// ```
/// fun_declaration := "fun" function
/// function := IDENTIFIER function_info
/// function_info := "(" parameters? ")" block
/// parameters := IDENTIFIER ( "," IDENTIFIER )*
/// ```
/// The `kind` parameter is used to generate error messages.
fn parse_fun_declaration(&mut self, kind: &'static str) -> ParserResult<ast::StmtNode> {
// Read the name
let name = match self.peek().token_type {
TokenType::Identifier(_) => self.advance().clone(),
_ => {
return Err(ParserError::new(
self.peek(),
&format!("expected {} name", kind),
))
}
};
// Read the list of parameter names
self.consume(
&TokenType::LeftParen,
&format!("expected '(' after {} name", kind),
)?;
let params = {
let mut params = Vec::new();
if !self.check(&TokenType::RightParen) {
loop {
if params.len() >= 255 {
return Err(ParserError::new(
self.peek(),
&format!("{} can't have more than 255 parameters", kind),
));
}
if let TokenType::Identifier(_) = self.peek().token_type {
params.push(self.advance().clone());
} else {
return Err(ParserError::new(self.peek(), "parameter name expected"));
}
if self.expect(&[TokenType::Comma]).is_none() {
break;
}
}
self.consume(&TokenType::RightParen, "')' expected after parameters")?;
}
params
};
// Read the function's body
self.consume(
&TokenType::LeftBrace,
&format!("'{{' expected before {} body", kind),
)?;
let block = self.parse_block()?;
Ok(ast::StmtNode::FunDecl {
name,
params,
body: block.extract_block_statements(),
})
}
/// Parse the following rule:
/// ```
/// block := "{" statement* "}"