1 use parse::token::{Token, BinOpToken};
3 use ast::{self, BinOpKind};
5 /// Associative operator with precedence.
7 /// This is the enum which specifies operator precedence and fixity to the parser.
8 #[derive(PartialEq, Debug)]
50 /// `?=` where ? is one of the BinOpToken
62 #[derive(PartialEq, Debug)]
64 /// The operator is left-associative
66 /// The operator is right-associative
68 /// The operator is not associative
73 /// Create a new AssocOP from a token
74 pub fn from_token(t: &Token) -> Option<AssocOp> {
77 Token::BinOpEq(k) => Some(AssignOp(k)),
78 Token::LArrow => Some(ObsoleteInPlace),
79 Token::Eq => Some(Assign),
80 Token::BinOp(BinOpToken::Star) => Some(Multiply),
81 Token::BinOp(BinOpToken::Slash) => Some(Divide),
82 Token::BinOp(BinOpToken::Percent) => Some(Modulus),
83 Token::BinOp(BinOpToken::Plus) => Some(Add),
84 Token::BinOp(BinOpToken::Minus) => Some(Subtract),
85 Token::BinOp(BinOpToken::Shl) => Some(ShiftLeft),
86 Token::BinOp(BinOpToken::Shr) => Some(ShiftRight),
87 Token::BinOp(BinOpToken::And) => Some(BitAnd),
88 Token::BinOp(BinOpToken::Caret) => Some(BitXor),
89 Token::BinOp(BinOpToken::Or) => Some(BitOr),
90 Token::Lt => Some(Less),
91 Token::Le => Some(LessEqual),
92 Token::Ge => Some(GreaterEqual),
93 Token::Gt => Some(Greater),
94 Token::EqEq => Some(Equal),
95 Token::Ne => Some(NotEqual),
96 Token::AndAnd => Some(LAnd),
97 Token::OrOr => Some(LOr),
98 Token::DotDot => Some(DotDot),
99 Token::DotDotEq => Some(DotDotEq),
100 // DotDotDot is no longer supported, but we need some way to display the error
101 Token::DotDotDot => Some(DotDotEq),
102 Token::Colon => Some(Colon),
103 _ if t.is_keyword(keywords::As) => Some(As),
108 /// Create a new AssocOp from ast::BinOpKind.
109 pub fn from_ast_binop(op: BinOpKind) -> Self {
110 use self::AssocOp::*;
112 BinOpKind::Lt => Less,
113 BinOpKind::Gt => Greater,
114 BinOpKind::Le => LessEqual,
115 BinOpKind::Ge => GreaterEqual,
116 BinOpKind::Eq => Equal,
117 BinOpKind::Ne => NotEqual,
118 BinOpKind::Mul => Multiply,
119 BinOpKind::Div => Divide,
120 BinOpKind::Rem => Modulus,
121 BinOpKind::Add => Add,
122 BinOpKind::Sub => Subtract,
123 BinOpKind::Shl => ShiftLeft,
124 BinOpKind::Shr => ShiftRight,
125 BinOpKind::BitAnd => BitAnd,
126 BinOpKind::BitXor => BitXor,
127 BinOpKind::BitOr => BitOr,
128 BinOpKind::And => LAnd,
133 /// Gets the precedence of this operator
134 pub fn precedence(&self) -> usize {
135 use self::AssocOp::*;
138 Multiply | Divide | Modulus => 13,
139 Add | Subtract => 12,
140 ShiftLeft | ShiftRight => 11,
144 Less | Greater | LessEqual | GreaterEqual | Equal | NotEqual => 7,
147 DotDot | DotDotEq => 4,
148 ObsoleteInPlace => 3,
149 Assign | AssignOp(_) => 2,
153 /// Gets the fixity of this operator
154 pub fn fixity(&self) -> Fixity {
155 use self::AssocOp::*;
156 // NOTE: it is a bug to have an operators that has same precedence but different fixities!
158 ObsoleteInPlace | Assign | AssignOp(_) => Fixity::Right,
159 As | Multiply | Divide | Modulus | Add | Subtract | ShiftLeft | ShiftRight | BitAnd |
160 BitXor | BitOr | Less | Greater | LessEqual | GreaterEqual | Equal | NotEqual |
161 LAnd | LOr | Colon => Fixity::Left,
162 DotDot | DotDotEq => Fixity::None
166 pub fn is_comparison(&self) -> bool {
167 use self::AssocOp::*;
169 Less | Greater | LessEqual | GreaterEqual | Equal | NotEqual => true,
170 ObsoleteInPlace | Assign | AssignOp(_) | As | Multiply | Divide | Modulus | Add |
171 Subtract | ShiftLeft | ShiftRight | BitAnd | BitXor | BitOr | LAnd | LOr |
172 DotDot | DotDotEq | Colon => false
176 pub fn is_assign_like(&self) -> bool {
177 use self::AssocOp::*;
179 Assign | AssignOp(_) | ObsoleteInPlace => true,
180 Less | Greater | LessEqual | GreaterEqual | Equal | NotEqual | As | Multiply | Divide |
181 Modulus | Add | Subtract | ShiftLeft | ShiftRight | BitAnd | BitXor | BitOr | LAnd |
182 LOr | DotDot | DotDotEq | Colon => false
186 pub fn to_ast_binop(&self) -> Option<BinOpKind> {
187 use self::AssocOp::*;
189 Less => Some(BinOpKind::Lt),
190 Greater => Some(BinOpKind::Gt),
191 LessEqual => Some(BinOpKind::Le),
192 GreaterEqual => Some(BinOpKind::Ge),
193 Equal => Some(BinOpKind::Eq),
194 NotEqual => Some(BinOpKind::Ne),
195 Multiply => Some(BinOpKind::Mul),
196 Divide => Some(BinOpKind::Div),
197 Modulus => Some(BinOpKind::Rem),
198 Add => Some(BinOpKind::Add),
199 Subtract => Some(BinOpKind::Sub),
200 ShiftLeft => Some(BinOpKind::Shl),
201 ShiftRight => Some(BinOpKind::Shr),
202 BitAnd => Some(BinOpKind::BitAnd),
203 BitXor => Some(BinOpKind::BitXor),
204 BitOr => Some(BinOpKind::BitOr),
205 LAnd => Some(BinOpKind::And),
206 LOr => Some(BinOpKind::Or),
207 ObsoleteInPlace | Assign | AssignOp(_) | As | DotDot | DotDotEq | Colon => None
212 pub const PREC_RESET: i8 = -100;
213 pub const PREC_CLOSURE: i8 = -40;
214 pub const PREC_JUMP: i8 = -30;
215 pub const PREC_RANGE: i8 = -10;
216 // The range 2 ... 14 is reserved for AssocOp binary operator precedences.
217 pub const PREC_PREFIX: i8 = 50;
218 pub const PREC_POSTFIX: i8 = 60;
219 pub const PREC_PAREN: i8 = 99;
220 pub const PREC_FORCE_PAREN: i8 = 100;
222 #[derive(Debug, Clone, Copy)]
223 pub enum ExprPrecedence {
272 impl ExprPrecedence {
273 pub fn order(self) -> i8 {
275 ExprPrecedence::Closure => PREC_CLOSURE,
277 ExprPrecedence::Break |
278 ExprPrecedence::Continue |
279 ExprPrecedence::Ret |
280 ExprPrecedence::Yield => PREC_JUMP,
282 // `Range` claims to have higher precedence than `Assign`, but `x .. x = x` fails to
283 // parse, instead of parsing as `(x .. x) = x`. Giving `Range` a lower precedence
284 // ensures that `pprust` will add parentheses in the right places to get the desired
286 ExprPrecedence::Range => PREC_RANGE,
288 // Binop-like expr kinds, handled by `AssocOp`.
289 ExprPrecedence::Binary(op) => AssocOp::from_ast_binop(op).precedence() as i8,
290 ExprPrecedence::ObsoleteInPlace => AssocOp::ObsoleteInPlace.precedence() as i8,
291 ExprPrecedence::Cast => AssocOp::As.precedence() as i8,
292 ExprPrecedence::Type => AssocOp::Colon.precedence() as i8,
294 ExprPrecedence::Assign |
295 ExprPrecedence::AssignOp => AssocOp::Assign.precedence() as i8,
298 ExprPrecedence::Box |
299 ExprPrecedence::AddrOf |
300 ExprPrecedence::Unary => PREC_PREFIX,
303 ExprPrecedence::Call |
304 ExprPrecedence::MethodCall |
305 ExprPrecedence::Field |
306 ExprPrecedence::Index |
307 ExprPrecedence::Try |
308 ExprPrecedence::InlineAsm |
309 ExprPrecedence::Mac => PREC_POSTFIX,
312 ExprPrecedence::Array |
313 ExprPrecedence::Repeat |
314 ExprPrecedence::Tup |
315 ExprPrecedence::Lit |
316 ExprPrecedence::Path |
317 ExprPrecedence::Paren |
319 ExprPrecedence::IfLet |
320 ExprPrecedence::While |
321 ExprPrecedence::WhileLet |
322 ExprPrecedence::ForLoop |
323 ExprPrecedence::Loop |
324 ExprPrecedence::Match |
325 ExprPrecedence::Block |
326 ExprPrecedence::TryBlock |
327 ExprPrecedence::Async |
328 ExprPrecedence::Struct => PREC_PAREN,
334 /// Expressions that syntactically contain an "exterior" struct literal i.e., not surrounded by any
335 /// parens or other delimiters, e.g., `X { y: 1 }`, `X { y: 1 }.method()`, `foo == X { y: 1 }` and
336 /// `X { y: 1 } == foo` all do, but `(X { y: 1 }) == foo` does not.
337 pub fn contains_exterior_struct_lit(value: &ast::Expr) -> bool {
339 ast::ExprKind::Struct(..) => true,
341 ast::ExprKind::Assign(ref lhs, ref rhs) |
342 ast::ExprKind::AssignOp(_, ref lhs, ref rhs) |
343 ast::ExprKind::Binary(_, ref lhs, ref rhs) => {
344 // X { y: 1 } + X { y: 2 }
345 contains_exterior_struct_lit(&lhs) || contains_exterior_struct_lit(&rhs)
347 ast::ExprKind::Unary(_, ref x) |
348 ast::ExprKind::Cast(ref x, _) |
349 ast::ExprKind::Type(ref x, _) |
350 ast::ExprKind::Field(ref x, _) |
351 ast::ExprKind::Index(ref x, _) => {
352 // &X { y: 1 }, X { y: 1 }.y
353 contains_exterior_struct_lit(&x)
356 ast::ExprKind::MethodCall(.., ref exprs) => {
357 // X { y: 1 }.bar(...)
358 contains_exterior_struct_lit(&exprs[0])