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467 lines
17 KiB
467 lines
17 KiB
/**
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* @fileoverview Abstraction of JavaScript source code.
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* @author Nicholas C. Zakas
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Requirements
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//------------------------------------------------------------------------------
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const TokenStore = require("../token-store"),
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Traverser = require("./traverser"),
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astUtils = require("../ast-utils"),
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lodash = require("lodash");
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//------------------------------------------------------------------------------
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// Private
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//------------------------------------------------------------------------------
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/**
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* Validates that the given AST has the required information.
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* @param {ASTNode} ast The Program node of the AST to check.
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* @throws {Error} If the AST doesn't contain the correct information.
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* @returns {void}
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* @private
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*/
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function validate(ast) {
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if (!ast.tokens) {
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throw new Error("AST is missing the tokens array.");
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}
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if (!ast.comments) {
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throw new Error("AST is missing the comments array.");
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}
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if (!ast.loc) {
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throw new Error("AST is missing location information.");
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}
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if (!ast.range) {
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throw new Error("AST is missing range information");
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}
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}
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/**
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* Finds a JSDoc comment node in an array of comment nodes.
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* @param {ASTNode[]} comments The array of comment nodes to search.
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* @param {int} line Line number to look around
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* @returns {ASTNode} The node if found, null if not.
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* @private
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*/
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function findJSDocComment(comments, line) {
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if (comments) {
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for (let i = comments.length - 1; i >= 0; i--) {
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if (comments[i].type === "Block" && comments[i].value.charAt(0) === "*") {
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if (line - comments[i].loc.end.line <= 1) {
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return comments[i];
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}
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break;
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}
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}
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}
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return null;
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}
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/**
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* Check to see if its a ES6 export declaration
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* @param {ASTNode} astNode - any node
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* @returns {boolean} whether the given node represents a export declaration
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* @private
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*/
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function looksLikeExport(astNode) {
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return astNode.type === "ExportDefaultDeclaration" || astNode.type === "ExportNamedDeclaration" ||
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astNode.type === "ExportAllDeclaration" || astNode.type === "ExportSpecifier";
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}
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/**
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* Merges two sorted lists into a larger sorted list in O(n) time
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* @param {Token[]} tokens The list of tokens
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* @param {Token[]} comments The list of comments
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* @returns {Token[]} A sorted list of tokens and comments
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*/
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function sortedMerge(tokens, comments) {
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const result = [];
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let tokenIndex = 0;
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let commentIndex = 0;
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while (tokenIndex < tokens.length || commentIndex < comments.length) {
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if (commentIndex >= comments.length || tokenIndex < tokens.length && tokens[tokenIndex].range[0] < comments[commentIndex].range[0]) {
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result.push(tokens[tokenIndex++]);
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} else {
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result.push(comments[commentIndex++]);
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}
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}
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return result;
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}
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//------------------------------------------------------------------------------
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// Public Interface
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//------------------------------------------------------------------------------
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class SourceCode extends TokenStore {
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/**
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* Represents parsed source code.
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* @param {string} text - The source code text.
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* @param {ASTNode} ast - The Program node of the AST representing the code. This AST should be created from the text that BOM was stripped.
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* @constructor
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*/
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constructor(text, ast) {
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validate(ast);
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super(ast.tokens, ast.comments);
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/**
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* The flag to indicate that the source code has Unicode BOM.
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* @type boolean
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*/
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this.hasBOM = (text.charCodeAt(0) === 0xFEFF);
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/**
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* The original text source code.
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* BOM was stripped from this text.
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* @type string
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*/
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this.text = (this.hasBOM ? text.slice(1) : text);
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/**
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* The parsed AST for the source code.
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* @type ASTNode
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*/
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this.ast = ast;
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// Check the source text for the presence of a shebang since it is parsed as a standard line comment.
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const shebangMatched = this.text.match(astUtils.SHEBANG_MATCHER);
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const hasShebang = shebangMatched && ast.comments.length && ast.comments[0].value === shebangMatched[1];
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if (hasShebang) {
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ast.comments[0].type = "Shebang";
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}
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this.tokensAndComments = sortedMerge(ast.tokens, ast.comments);
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/**
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* The source code split into lines according to ECMA-262 specification.
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* This is done to avoid each rule needing to do so separately.
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* @type string[]
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*/
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this.lines = [];
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this.lineStartIndices = [0];
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const lineEndingPattern = astUtils.createGlobalLinebreakMatcher();
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let match;
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/*
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* Previously, this was implemented using a regex that
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* matched a sequence of non-linebreak characters followed by a
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* linebreak, then adding the lengths of the matches. However,
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* this caused a catastrophic backtracking issue when the end
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* of a file contained a large number of non-newline characters.
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* To avoid this, the current implementation just matches newlines
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* and uses match.index to get the correct line start indices.
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*/
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while ((match = lineEndingPattern.exec(this.text))) {
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this.lines.push(this.text.slice(this.lineStartIndices[this.lineStartIndices.length - 1], match.index));
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this.lineStartIndices.push(match.index + match[0].length);
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}
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this.lines.push(this.text.slice(this.lineStartIndices[this.lineStartIndices.length - 1]));
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// Cache for comments found using getComments().
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this._commentCache = new WeakMap();
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// don't allow modification of this object
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Object.freeze(this);
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Object.freeze(this.lines);
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}
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/**
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* Split the source code into multiple lines based on the line delimiters
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* @param {string} text Source code as a string
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* @returns {string[]} Array of source code lines
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* @public
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*/
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static splitLines(text) {
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return text.split(astUtils.createGlobalLinebreakMatcher());
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}
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/**
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* Gets the source code for the given node.
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* @param {ASTNode=} node The AST node to get the text for.
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* @param {int=} beforeCount The number of characters before the node to retrieve.
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* @param {int=} afterCount The number of characters after the node to retrieve.
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* @returns {string} The text representing the AST node.
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*/
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getText(node, beforeCount, afterCount) {
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if (node) {
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return this.text.slice(Math.max(node.range[0] - (beforeCount || 0), 0),
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node.range[1] + (afterCount || 0));
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}
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return this.text;
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}
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/**
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* Gets the entire source text split into an array of lines.
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* @returns {Array} The source text as an array of lines.
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*/
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getLines() {
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return this.lines;
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}
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/**
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* Retrieves an array containing all comments in the source code.
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* @returns {ASTNode[]} An array of comment nodes.
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*/
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getAllComments() {
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return this.ast.comments;
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}
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/**
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* Gets all comments for the given node.
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* @param {ASTNode} node The AST node to get the comments for.
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* @returns {Object} The list of comments indexed by their position.
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* @public
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*/
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getComments(node) {
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if (this._commentCache.has(node)) {
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return this._commentCache.get(node);
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}
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const comments = {
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leading: [],
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trailing: []
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};
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/*
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* Return all comments as leading comments of the Program node when
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* there is no executable code.
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*/
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if (node.type === "Program") {
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if (node.body.length === 0) {
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comments.leading = node.comments;
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}
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} else {
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/* Return comments as trailing comments of nodes that only contain
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* comments (to mimic the comment attachment behavior present in Espree).
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*/
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if ((node.type === "BlockStatement" || node.type === "ClassBody") && node.body.length === 0 ||
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node.type === "ObjectExpression" && node.properties.length === 0 ||
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node.type === "ArrayExpression" && node.elements.length === 0 ||
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node.type === "SwitchStatement" && node.cases.length === 0
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) {
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comments.trailing = this.getTokens(node, {
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includeComments: true,
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filter: astUtils.isCommentToken
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});
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}
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/*
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* Iterate over tokens before and after node and collect comment tokens.
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* Do not include comments that exist outside of the parent node
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* to avoid duplication.
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*/
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let currentToken = this.getTokenBefore(node, { includeComments: true });
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while (currentToken && astUtils.isCommentToken(currentToken)) {
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if (node.parent && (currentToken.start < node.parent.start)) {
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break;
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}
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comments.leading.push(currentToken);
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currentToken = this.getTokenBefore(currentToken, { includeComments: true });
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}
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comments.leading.reverse();
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currentToken = this.getTokenAfter(node, { includeComments: true });
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while (currentToken && astUtils.isCommentToken(currentToken)) {
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if (node.parent && (currentToken.end > node.parent.end)) {
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break;
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}
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comments.trailing.push(currentToken);
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currentToken = this.getTokenAfter(currentToken, { includeComments: true });
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}
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}
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this._commentCache.set(node, comments);
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return comments;
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}
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/**
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* Retrieves the JSDoc comment for a given node.
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* @param {ASTNode} node The AST node to get the comment for.
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* @returns {ASTNode} The Block comment node containing the JSDoc for the
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* given node or null if not found.
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* @public
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*/
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getJSDocComment(node) {
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let parent = node.parent;
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const leadingComments = this.getCommentsBefore(node);
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switch (node.type) {
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case "ClassDeclaration":
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case "FunctionDeclaration":
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if (looksLikeExport(parent)) {
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return findJSDocComment(this.getCommentsBefore(parent), parent.loc.start.line);
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}
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return findJSDocComment(leadingComments, node.loc.start.line);
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case "ClassExpression":
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return findJSDocComment(this.getCommentsBefore(parent.parent), parent.parent.loc.start.line);
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case "ArrowFunctionExpression":
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case "FunctionExpression":
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if (parent.type !== "CallExpression" && parent.type !== "NewExpression") {
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let parentLeadingComments = this.getCommentsBefore(parent);
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while (!parentLeadingComments.length && !/Function/.test(parent.type) && parent.type !== "MethodDefinition" && parent.type !== "Property") {
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parent = parent.parent;
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if (!parent) {
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break;
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}
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parentLeadingComments = this.getCommentsBefore(parent);
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}
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return parent && parent.type !== "FunctionDeclaration" && parent.type !== "Program" ? findJSDocComment(parentLeadingComments, parent.loc.start.line) : null;
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} else if (leadingComments.length) {
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return findJSDocComment(leadingComments, node.loc.start.line);
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}
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// falls through
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default:
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return null;
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}
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}
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/**
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* Gets the deepest node containing a range index.
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* @param {int} index Range index of the desired node.
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* @returns {ASTNode} The node if found or null if not found.
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*/
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getNodeByRangeIndex(index) {
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let result = null,
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resultParent = null;
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const traverser = new Traverser();
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traverser.traverse(this.ast, {
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enter(node, parent) {
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if (node.range[0] <= index && index < node.range[1]) {
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result = node;
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resultParent = parent;
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} else {
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this.skip();
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}
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},
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leave(node) {
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if (node === result) {
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this.break();
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}
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}
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});
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return result ? Object.assign({ parent: resultParent }, result) : null;
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}
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/**
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* Determines if two tokens have at least one whitespace character
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* between them. This completely disregards comments in making the
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* determination, so comments count as zero-length substrings.
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* @param {Token} first The token to check after.
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* @param {Token} second The token to check before.
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* @returns {boolean} True if there is only space between tokens, false
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* if there is anything other than whitespace between tokens.
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*/
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isSpaceBetweenTokens(first, second) {
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const text = this.text.slice(first.range[1], second.range[0]);
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return /\s/.test(text.replace(/\/\*.*?\*\//g, ""));
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}
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/**
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* Converts a source text index into a (line, column) pair.
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* @param {number} index The index of a character in a file
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* @returns {Object} A {line, column} location object with a 0-indexed column
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*/
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getLocFromIndex(index) {
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if (typeof index !== "number") {
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throw new TypeError("Expected `index` to be a number.");
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}
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if (index < 0 || index > this.text.length) {
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throw new RangeError(`Index out of range (requested index ${index}, but source text has length ${this.text.length}).`);
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}
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/*
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* For an argument of this.text.length, return the location one "spot" past the last character
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* of the file. If the last character is a linebreak, the location will be column 0 of the next
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* line; otherwise, the location will be in the next column on the same line.
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*
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* See getIndexFromLoc for the motivation for this special case.
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*/
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if (index === this.text.length) {
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return { line: this.lines.length, column: this.lines[this.lines.length - 1].length };
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}
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/*
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* To figure out which line rangeIndex is on, determine the last index at which rangeIndex could
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* be inserted into lineIndices to keep the list sorted.
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*/
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const lineNumber = lodash.sortedLastIndex(this.lineStartIndices, index);
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return { line: lineNumber, column: index - this.lineStartIndices[lineNumber - 1] };
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}
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/**
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* Converts a (line, column) pair into a range index.
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* @param {Object} loc A line/column location
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* @param {number} loc.line The line number of the location (1-indexed)
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* @param {number} loc.column The column number of the location (0-indexed)
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* @returns {number} The range index of the location in the file.
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*/
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getIndexFromLoc(loc) {
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if (typeof loc !== "object" || typeof loc.line !== "number" || typeof loc.column !== "number") {
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throw new TypeError("Expected `loc` to be an object with numeric `line` and `column` properties.");
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}
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if (loc.line <= 0) {
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throw new RangeError(`Line number out of range (line ${loc.line} requested). Line numbers should be 1-based.`);
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}
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if (loc.line > this.lineStartIndices.length) {
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throw new RangeError(`Line number out of range (line ${loc.line} requested, but only ${this.lineStartIndices.length} lines present).`);
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}
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const lineStartIndex = this.lineStartIndices[loc.line - 1];
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const lineEndIndex = loc.line === this.lineStartIndices.length ? this.text.length : this.lineStartIndices[loc.line];
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const positionIndex = lineStartIndex + loc.column;
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/*
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* By design, getIndexFromLoc({ line: lineNum, column: 0 }) should return the start index of
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* the given line, provided that the line number is valid element of this.lines. Since the
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* last element of this.lines is an empty string for files with trailing newlines, add a
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* special case where getting the index for the first location after the end of the file
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* will return the length of the file, rather than throwing an error. This allows rules to
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* use getIndexFromLoc consistently without worrying about edge cases at the end of a file.
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*/
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if (
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loc.line === this.lineStartIndices.length && positionIndex > lineEndIndex ||
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loc.line < this.lineStartIndices.length && positionIndex >= lineEndIndex
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) {
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throw new RangeError(`Column number out of range (column ${loc.column} requested, but the length of line ${loc.line} is ${lineEndIndex - lineStartIndex}).`);
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}
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return positionIndex;
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}
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}
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module.exports = SourceCode;
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