123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193
'use strict';
// --------------------------------------------------------------------// Imports// --------------------------------------------------------------------
const Grammar = require('./Grammar');const InputStream = require('./InputStream');const common = require('./common');const errors = require('./errors');const pexprs = require('./pexprs');
// --------------------------------------------------------------------// Private Stuff// --------------------------------------------------------------------
// Constructors
function GrammarDecl(name) {  this.name = name;}
// Helpers
GrammarDecl.prototype.sourceInterval = function(startIdx, endIdx) {  return this.source.subInterval(startIdx, endIdx - startIdx);};
GrammarDecl.prototype.ensureSuperGrammar = function() {  if (!this.superGrammar) {    this.withSuperGrammar(      // TODO: The conditional expression below is an ugly hack. It's kind of ok because      // I doubt anyone will ever try to declare a grammar called `BuiltInRules`. Still,      // we should try to find a better way to do this.      this.name === 'BuiltInRules' ? Grammar.ProtoBuiltInRules : Grammar.BuiltInRules    );  }  return this.superGrammar;};
GrammarDecl.prototype.ensureSuperGrammarRuleForOverriding = function(name, source) {  const ruleInfo = this.ensureSuperGrammar().rules[name];  if (!ruleInfo) {    throw errors.cannotOverrideUndeclaredRule(name, this.superGrammar.name, source);  }  return ruleInfo;};
GrammarDecl.prototype.installOverriddenOrExtendedRule = function(    name,    formals,    body,    source) {  const duplicateParameterNames = common.getDuplicates(formals);  if (duplicateParameterNames.length > 0) {    throw errors.duplicateParameterNames(name, duplicateParameterNames, source);  }  const ruleInfo = this.ensureSuperGrammar().rules[name];  const expectedFormals = ruleInfo.formals;  const expectedNumFormals = expectedFormals ? expectedFormals.length : 0;  if (formals.length !== expectedNumFormals) {    throw errors.wrongNumberOfParameters(name, expectedNumFormals, formals.length, source);  }  return this.install(name, formals, body, ruleInfo.description, source);};
GrammarDecl.prototype.install = function(name, formals, body, description, source) {  this.rules[name] = {    body: body.introduceParams(formals),    formals,    description,    source,  };  return this;};
// Stuff that you should only do once
GrammarDecl.prototype.withSuperGrammar = function(superGrammar) {  if (this.superGrammar) {    throw new Error('the super grammar of a GrammarDecl cannot be set more than once');  }  this.superGrammar = superGrammar;  this.rules = Object.create(superGrammar.rules);
  // Grammars with an explicit supergrammar inherit a default start rule.  if (!superGrammar.isBuiltIn()) {    this.defaultStartRule = superGrammar.defaultStartRule;  }  return this;};
GrammarDecl.prototype.withDefaultStartRule = function(ruleName) {  this.defaultStartRule = ruleName;  return this;};
GrammarDecl.prototype.withSource = function(source) {  this.source = new InputStream(source).interval(0, source.length);  return this;};
// Creates a Grammar instance, and if it passes the sanity checks, returns it.GrammarDecl.prototype.build = function() {  const grammar = new Grammar(      this.name,      this.ensureSuperGrammar(),      this.rules,      this.defaultStartRule  );
  // TODO: change the pexpr.prototype.assert... methods to make them add  // exceptions to an array that's provided as an arg. Then we'll be able to  // show more than one error of the same type at a time.  // TODO: include the offending pexpr in the errors, that way we can show  // the part of the source that caused it.  const grammarErrors = [];  let grammarHasInvalidApplications = false;  Object.keys(grammar.rules).forEach(ruleName => {    const {body} = grammar.rules[ruleName];    try {      body.assertChoicesHaveUniformArity(ruleName);    } catch (e) {      grammarErrors.push(e);    }    try {      body.assertAllApplicationsAreValid(ruleName, grammar);    } catch (e) {      grammarErrors.push(e);      grammarHasInvalidApplications = true;    }  });  if (!grammarHasInvalidApplications) {    // The following check can only be done if the grammar has no invalid applications.    Object.keys(grammar.rules).forEach(ruleName => {      const {body} = grammar.rules[ruleName];      try {        body.assertIteratedExprsAreNotNullable(grammar, []);      } catch (e) {        grammarErrors.push(e);      }    });  }  if (grammarErrors.length > 0) {    errors.throwErrors(grammarErrors);  }  if (this.source) {    grammar.source = this.source;  }
  return grammar;};
// Rule declarations
GrammarDecl.prototype.define = function(name, formals, body, description, source) {  this.ensureSuperGrammar();  if (this.superGrammar.rules[name]) {    throw errors.duplicateRuleDeclaration(name, this.name, this.superGrammar.name, source);  } else if (this.rules[name]) {    throw errors.duplicateRuleDeclaration(name, this.name, this.name, source);  }  const duplicateParameterNames = common.getDuplicates(formals);  if (duplicateParameterNames.length > 0) {    throw errors.duplicateParameterNames(name, duplicateParameterNames, source);  }  return this.install(name, formals, body, description, source);};
GrammarDecl.prototype.override = function(name, formals, body, descIgnored, source) {  this.ensureSuperGrammarRuleForOverriding(name, source);  this.installOverriddenOrExtendedRule(name, formals, body, source);  return this;};
GrammarDecl.prototype.extend = function(name, formals, fragment, descIgnored, source) {  const ruleInfo = this.ensureSuperGrammar().rules[name];  if (!ruleInfo) {    throw errors.cannotExtendUndeclaredRule(name, this.superGrammar.name, source);  }  const body = new pexprs.Extend(this.superGrammar, name, fragment);  body.source = fragment.source;  this.installOverriddenOrExtendedRule(name, formals, body, source);  return this;};
// --------------------------------------------------------------------// Exports// --------------------------------------------------------------------
module.exports = GrammarDecl;