You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
77 lines
1.5 KiB
JavaScript
77 lines
1.5 KiB
JavaScript
"use strict";
|
|
|
|
let visitor = require("./visitor");
|
|
|
|
// AST utilities.
|
|
let asts = {
|
|
findRule(ast, name) {
|
|
for (let i = 0; i < ast.rules.length; i++) {
|
|
if (ast.rules[i].name === name) {
|
|
return ast.rules[i];
|
|
}
|
|
}
|
|
|
|
return undefined;
|
|
},
|
|
|
|
indexOfRule(ast, name) {
|
|
for (let i = 0; i < ast.rules.length; i++) {
|
|
if (ast.rules[i].name === name) {
|
|
return i;
|
|
}
|
|
}
|
|
|
|
return -1;
|
|
},
|
|
|
|
alwaysConsumesOnSuccess(ast, node) {
|
|
function consumesTrue() { return true; }
|
|
function consumesFalse() { return false; }
|
|
|
|
function consumesExpression(node) {
|
|
return consumes(node.expression);
|
|
}
|
|
|
|
let consumes = visitor.build({
|
|
rule: consumesExpression,
|
|
named: consumesExpression,
|
|
|
|
choice(node) {
|
|
return node.alternatives.every(consumes);
|
|
},
|
|
|
|
action: consumesExpression,
|
|
|
|
sequence(node) {
|
|
return node.elements.some(consumes);
|
|
},
|
|
|
|
labeled: consumesExpression,
|
|
text: consumesExpression,
|
|
simple_and: consumesFalse,
|
|
simple_not: consumesFalse,
|
|
optional: consumesFalse,
|
|
zero_or_more: consumesFalse,
|
|
one_or_more: consumesExpression,
|
|
group: consumesExpression,
|
|
semantic_and: consumesFalse,
|
|
semantic_not: consumesFalse,
|
|
|
|
rule_ref(node) {
|
|
return consumes(asts.findRule(ast, node.name));
|
|
},
|
|
|
|
literal(node) {
|
|
return node.value !== "";
|
|
},
|
|
|
|
class: consumesTrue,
|
|
any: consumesTrue
|
|
});
|
|
|
|
return consumes(node);
|
|
}
|
|
};
|
|
|
|
module.exports = asts;
|