svelte/src/utils/getExpressionPrecedence.ts

54 lines
1.2 KiB

import { Node } from '../interfaces';
const binaryOperators: Record<string, number> = {
'**': 15,
'*': 14,
'/': 14,
'%': 14,
'+': 13,
'-': 13,
'<<': 12,
'>>': 12,
'>>>': 12,
'<': 11,
'<=': 11,
'>': 11,
'>=': 11,
'in': 11,
'instanceof': 11,
'==': 10,
'!=': 10,
'===': 10,
'!==': 10,
'&': 9,
'^': 8,
'|': 7
};
const logicalOperators: Record<string, number> = {
'&&': 6,
'||': 5
};
const precedence: Record<string, (expression?: Node) => number> = {
Literal: () => 21,
Identifier: () => 21,
ParenthesizedExpression: () => 20,
MemberExpression: () => 19,
NewExpression: () => 19, // can be 18 (if no args) but makes no practical difference
CallExpression: () => 19,
UpdateExpression: () => 17,
UnaryExpression: () => 16,
BinaryExpression: (expression: Node) => binaryOperators[expression.operator],
LogicalExpression: (expression: Node) => logicalOperators[expression.operator],
ConditionalExpression: () => 4,
AssignmentExpression: () => 3,
YieldExpression: () => 2,
SpreadElement: () => 1,
SequenceExpression: () => 0
};
// TODO make this a method of Expression
export default function getExpressionPrecedence(expression: Node) {
return expression.type in precedence ? precedence[expression.type](expression) : 0;
}