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Made handling parse errors nicer

This commit is contained in:
greg 2017-09-30 14:41:37 -07:00
parent d05f173dd3
commit 6b9fee1aed
1 changed files with 33 additions and 35 deletions
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68
src/schala_lang/parsing.rs
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@ -370,16 +370,14 @@ impl Parser {
} }
macro_rules! expect { macro_rules! expect {
($self:expr, $token_type:pat, $message:expr) => { ($self:expr, $token_type:pat, $expected_item:expr) => { expect!($self, $token_type if true, $expected_item) };
match $self.peek() { ($self:expr, $token_type:pat if $cond:expr, $expected_item:expr) => {
$token_type => $self.next(),
_ => return Err(ParseError { msg: $message.to_string() }),
}
};
($self:expr, $token_type:pat if $cond:expr, $message:expr) => {
match $self.peek() { match $self.peek() {
$token_type if $cond => $self.next(), $token_type if $cond => $self.next(),
_ => return Err(ParseError { msg: $message.to_string() }), tok => {
let msg = format!("Expected {}, got {:?}", $expected_item, tok);
return Err(ParseError { msg })
}
} }
} }
} }
@ -503,15 +501,15 @@ macro_rules! parse_method {
} }
macro_rules! delimited { macro_rules! delimited {
($self:expr, $start:pat, $parse_fn:ident, $( $delim:pat )|+, $end:pat, nonstrict) => { ($self:expr, $start:pat, $start_str:expr, $parse_fn:ident, $( $delim:pat )|+, $end:pat, $end_str:expr, nonstrict) => {
delimited!($self, $start, $parse_fn, $( $delim )|*, $end, false) delimited!($self, $start, $start_str, $parse_fn, $( $delim )|*, $end, $end_str, false)
}; };
($self:expr, $start:pat, $parse_fn:ident, $( $delim:pat )|+, $end:pat) => { ($self:expr, $start:pat, $start_str:expr, $parse_fn:ident, $( $delim:pat )|+, $end:pat, $end_str:expr) => {
delimited!($self, $start, $parse_fn, $( $delim )|*, $end, true) delimited!($self, $start, $start_str, $parse_fn, $( $delim )|*, $end, $end_str, true)
}; };
($self:expr, $start:pat, $parse_fn:ident, $( $delim:pat )|+, $end:pat, $strictness:expr) => { ($self:expr, $start:pat, $start_str:expr, $parse_fn:ident, $( $delim:pat )|+, $end:pat, $end_str:expr, $strictness:expr) => {
{ {
expect!($self, $start, "Expected <start symbol figure out string interpol in macros>"); expect!($self, $start, $start_str);
let mut acc = vec![]; let mut acc = vec![];
loop { loop {
let peek = $self.peek(); let peek = $self.peek();
@ -531,7 +529,7 @@ macro_rules! delimited {
_ => break _ => break
}; };
} }
expect!($self, $end, "Expected <end symbol figure out string interpol in macros>"); expect!($self, $end, $end_str);
acc acc
} }
}; };
@ -565,17 +563,17 @@ impl Parser {
}); });
parse_method!(type_alias(&mut self) -> ParseResult<Declaration> { parse_method!(type_alias(&mut self) -> ParseResult<Declaration> {
expect!(self, Keyword(Alias), "Expected 'alias'"); expect!(self, Keyword(Alias), "'alias'");
let alias = self.identifier()?; let alias = self.identifier()?;
expect!(self, Operator(ref c) if **c == "=", "Expected '='"); expect!(self, Operator(ref c) if **c == "=", "'='");
let original = self.identifier()?; let original = self.identifier()?;
Ok(Declaration::TypeAlias(alias, original)) Ok(Declaration::TypeAlias(alias, original))
}); });
parse_method!(type_declaration(&mut self) -> ParseResult<Declaration> { parse_method!(type_declaration(&mut self) -> ParseResult<Declaration> {
expect!(self, Keyword(Type), "Expected 'type'"); expect!(self, Keyword(Type), "'type'");
let name = self.identifier()?; let name = self.identifier()?;
expect!(self, Operator(ref c) if **c == "=", "Expected '='"); expect!(self, Operator(ref c) if **c == "=", "'='");
let body = self.type_body()?; let body = self.type_body()?;
Ok(Declaration::TypeDecl(name, body)) Ok(Declaration::TypeDecl(name, body))
}); });
@ -586,11 +584,11 @@ impl Parser {
}); });
parse_method!(func_declaration(&mut self) -> ParseResult<Declaration> { parse_method!(func_declaration(&mut self) -> ParseResult<Declaration> {
expect!(self, Keyword(Func), "Expected 'fn'"); expect!(self, Keyword(Func), "'fn'");
let name = self.identifier()?; let name = self.identifier()?;
expect!(self, LParen, "Expected '('"); expect!(self, LParen, "'('");
let params = self.param_list()?; let params = self.param_list()?;
expect!(self, RParen, "Expected ')'"); expect!(self, RParen, "')'");
let decl = Declaration::FuncDecl { let decl = Declaration::FuncDecl {
name: name, name: name,
params: params params: params
@ -609,7 +607,7 @@ impl Parser {
_ => return ParseError::new("Expected 'var' or 'const'"), _ => return ParseError::new("Expected 'var' or 'const'"),
}; };
let name = self.identifier()?; let name = self.identifier()?;
expect!(self, Operator(ref o) if **o == "=", "Expected '='"); expect!(self, Operator(ref o) if **o == "=", "'='");
let expr = self.expression()?; let expr = self.expression()?;
Ok(Declaration::Binding { name, constant, expr }) Ok(Declaration::Binding { name, constant, expr })
@ -629,17 +627,17 @@ impl Parser {
}); });
parse_method!(type_anno(&mut self) -> ParseResult<TypeAnno> { parse_method!(type_anno(&mut self) -> ParseResult<TypeAnno> {
expect!(self, Colon, "Expected ':'"); expect!(self, Colon, "':'");
self.type_name() self.type_name()
}); });
parse_method!(type_name(&mut self) -> ParseResult<TypeAnno> { parse_method!(type_name(&mut self) -> ParseResult<TypeAnno> {
Ok(match self.peek() { Ok(match self.peek() {
LParen => TypeAnno::Tuple(delimited!(self, LParen, type_name, Comma, RParen)), LParen => TypeAnno::Tuple(delimited!(self, LParen, '(', type_name, Comma, RParen, ')')),
_ => TypeAnno::Singleton { _ => TypeAnno::Singleton {
name: self.identifier()?, name: self.identifier()?,
params: match self.peek() { params: match self.peek() {
LAngleBracket => delimited!(self, LAngleBracket, type_name, Comma, RAngleBracket), LAngleBracket => delimited!(self, LAngleBracket, '<', type_name, Comma, RAngleBracket, '>'),
_ => vec![], _ => vec![],
} }
} }
@ -705,9 +703,9 @@ impl Parser {
}); });
parse_method!(paren_expr(&mut self) -> ParseResult<Expression> { parse_method!(paren_expr(&mut self) -> ParseResult<Expression> {
expect!(self, LParen, "Expected '('"); expect!(self, LParen, "'('");
let expr = self.expression()?; let expr = self.expression()?;
expect!(self, RParen, "Expected ')'"); expect!(self, RParen, "')'");
Ok(expr) Ok(expr)
}); });
@ -734,15 +732,15 @@ impl Parser {
}); });
parse_method!(call_expr(&mut self) -> ParseResult<Vec<Expression>> { parse_method!(call_expr(&mut self) -> ParseResult<Vec<Expression>> {
Ok(delimited!(self, LParen, expression, Comma, RParen)) Ok(delimited!(self, LParen, ')', expression, Comma, RParen, '('))
}); });
parse_method!(index_expr(&mut self) -> ParseResult<Vec<Expression>> { parse_method!(index_expr(&mut self) -> ParseResult<Vec<Expression>> {
Ok(delimited!(self, LSquareBracket, expression, Comma, RSquareBracket)) Ok(delimited!(self, LSquareBracket, '[', expression, Comma, RSquareBracket, ']'))
}); });
parse_method!(if_expr(&mut self) -> ParseResult<Expression> { parse_method!(if_expr(&mut self) -> ParseResult<Expression> {
expect!(self, Keyword(Kw::If), "Expected 'if'"); expect!(self, Keyword(Kw::If), "'if'");
let condition = self.expression()?; let condition = self.expression()?;
let then_clause = self.block()?; let then_clause = self.block()?;
let else_clause = self.else_clause()?; let else_clause = self.else_clause()?;
@ -759,11 +757,11 @@ impl Parser {
}); });
parse_method!(block(&mut self) -> ParseResult<Vec<Statement>> { parse_method!(block(&mut self) -> ParseResult<Vec<Statement>> {
Ok(delimited!(self, LCurlyBrace, statement, Newline | Semicolon, RCurlyBrace, nonstrict)) Ok(delimited!(self, LCurlyBrace, '{', statement, Newline | Semicolon, RCurlyBrace, '}', nonstrict))
}); });
parse_method!(match_expr(&mut self) -> ParseResult<Expression> { parse_method!(match_expr(&mut self) -> ParseResult<Expression> {
expect!(self, Keyword(Kw::Match), "Expected 'match'"); expect!(self, Keyword(Kw::Match), "'match'");
let expr = self.expression()?; let expr = self.expression()?;
//TODO abstract these errors into the delimited macro //TODO abstract these errors into the delimited macro
//expect!(self, LCurlyBrace, "Expected '{'"); //expect!(self, LCurlyBrace, "Expected '{'");
@ -773,12 +771,12 @@ impl Parser {
}); });
parse_method!(match_body(&mut self) -> ParseResult<Vec<MatchArm>> { parse_method!(match_body(&mut self) -> ParseResult<Vec<MatchArm>> {
Ok(delimited!(self, LCurlyBrace, match_arm, Comma, RCurlyBrace)) Ok(delimited!(self, LCurlyBrace, '{', match_arm, Comma, RCurlyBrace, '}'))
}); });
parse_method!(match_arm(&mut self) -> ParseResult<MatchArm> { parse_method!(match_arm(&mut self) -> ParseResult<MatchArm> {
let pat = self.pattern()?; let pat = self.pattern()?;
expect!(self, Operator(ref c) if **c == "=>", "Expected '=>'"); expect!(self, Operator(ref c) if **c == "=>", "'=>'");
let expr = self.expression()?; let expr = self.expression()?;
Ok(MatchArm { pat, expr }) Ok(MatchArm { pat, expr })
}); });