chevrotain
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Chevrotain is a high performance fault tolerant javascript parsing DSL for building recursive decent parsers
89 lines • 4.54 kB
JavaScript
import { defineNameProp } from "../../lang/lang_extensions.js";
export function defaultVisit(ctx, param) {
const childrenNames = Object.keys(ctx);
const childrenNamesLength = childrenNames.length;
for (let i = 0; i < childrenNamesLength; i++) {
const currChildName = childrenNames[i];
const currChildArray = ctx[currChildName];
const currChildArrayLength = currChildArray.length;
for (let j = 0; j < currChildArrayLength; j++) {
const currChild = currChildArray[j];
// distinction between Tokens Children and CstNode children
if (currChild.tokenTypeIdx === undefined) {
this[currChild.name](currChild.children, param);
}
}
}
// defaultVisit does not support generic out param
}
export function createBaseSemanticVisitorConstructor(grammarName, ruleNames) {
const derivedConstructor = function () { };
// can be overwritten according to:
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/
// name?redirectlocale=en-US&redirectslug=JavaScript%2FReference%2FGlobal_Objects%2FFunction%2Fname
defineNameProp(derivedConstructor, grammarName + "BaseSemantics");
const semanticProto = {
visit: function (cstNode, param) {
// enables writing more concise visitor methods when CstNode has only a single child
if (Array.isArray(cstNode)) {
// A CST Node's children dictionary can never have empty arrays as values
// If a key is defined there will be at least one element in the corresponding value array.
cstNode = cstNode[0];
}
// enables passing optional CstNodes concisely.
if (cstNode === undefined) {
return undefined;
}
return this[cstNode.name](cstNode.children, param);
},
validateVisitor: function () {
const semanticDefinitionErrors = validateVisitor(this, ruleNames);
if (semanticDefinitionErrors.length !== 0) {
const errorMessages = semanticDefinitionErrors.map((currDefError) => currDefError.msg);
throw Error(`Errors Detected in CST Visitor <${this.constructor.name}>:\n\t` +
`${errorMessages.join("\n\n").replace(/\n/g, "\n\t")}`);
}
},
};
derivedConstructor.prototype = semanticProto;
derivedConstructor.prototype.constructor = derivedConstructor;
derivedConstructor._RULE_NAMES = ruleNames;
return derivedConstructor;
}
export function createBaseVisitorConstructorWithDefaults(grammarName, ruleNames, baseConstructor) {
const derivedConstructor = function () { };
// can be overwritten according to:
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/
// name?redirectlocale=en-US&redirectslug=JavaScript%2FReference%2FGlobal_Objects%2FFunction%2Fname
defineNameProp(derivedConstructor, grammarName + "BaseSemanticsWithDefaults");
const withDefaultsProto = Object.create(baseConstructor.prototype);
ruleNames.forEach((ruleName) => {
withDefaultsProto[ruleName] = defaultVisit;
});
derivedConstructor.prototype = withDefaultsProto;
derivedConstructor.prototype.constructor = derivedConstructor;
return derivedConstructor;
}
export var CstVisitorDefinitionError;
(function (CstVisitorDefinitionError) {
CstVisitorDefinitionError[CstVisitorDefinitionError["REDUNDANT_METHOD"] = 0] = "REDUNDANT_METHOD";
CstVisitorDefinitionError[CstVisitorDefinitionError["MISSING_METHOD"] = 1] = "MISSING_METHOD";
})(CstVisitorDefinitionError || (CstVisitorDefinitionError = {}));
export function validateVisitor(visitorInstance, ruleNames) {
const missingErrors = validateMissingCstMethods(visitorInstance, ruleNames);
return missingErrors;
}
export function validateMissingCstMethods(visitorInstance, ruleNames) {
const missingRuleNames = ruleNames.filter((currRuleName) => {
return ((typeof visitorInstance[currRuleName] === "function") === false);
});
const errors = missingRuleNames.map((currRuleName) => {
return {
msg: `Missing visitor method: <${currRuleName}> on ${(visitorInstance.constructor.name)} CST Visitor.`,
type: CstVisitorDefinitionError.MISSING_METHOD,
methodName: currRuleName,
};
});
return errors.filter(Boolean);
}
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