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Update grammar definition

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This commit is contained in:
Daniel M 2022-01-28 14:00:51 +01:00
parent 7b86fecc6f
commit 807482583a
1 changed files with 12 additions and 4 deletions
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16
src/parser.rs
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@ -47,10 +47,14 @@ pub enum Ast {
/*
## Grammar
### Expressions
`expr_primary = LITERAL` \
`expr_mul = expr_primary (("*" | "/") expr_primary)*` \
`expr_add = expr_mul (("+" | "-") expr_mul)*` \
`expr = expr_add` \
expr_primary = LITERAL
expr_mul = expr_primary (("*" | "/" | "%") expr_primary)*
expr_add = expr_mul (("+" | "-") expr_mul)*
expr_shift = expr_add ((">>" | "<<") expr_add)*
expr_band = expr_shift ("&" expr_shift)*
expr_bxor = expr_band ("^") expr_band)*
expr_bor = expr_bxor ("|" expr_bxor)*
expr = expr_bor
*/
struct Parser<T: Iterator<Item = Token>> {
@ -129,6 +133,10 @@ pub fn parse<T: Iterator<Item = Token>, A: IntoIterator<IntoIter = T>>(tokens: A
impl BinOpType {
/// Get the precedence for a binary operator. Higher value means the OP is stronger binding.
/// For example Multiplication is stronger than addition, so Mul has higher precedence than Add.
///
/// The operator precedences are derived from the C language operator precedences. While not all
/// C operators are included or the exact same, the precedence oder is the same.
/// See: https://en.cppreference.com/w/c/language/operator_precedence
fn precedence(&self) -> u8 {
match self {
BinOpType::BOr => 0,