New: external reference analysis

Author: mysticatea

docs/ast.md

@@ -57,11 +57,18 @@ interface VExpressionContainer <: Node {
     type: "VExpressionContainer"
     expression: Expression | null
     syntaxError: Error | null
+    references: [ Reference ]
+}
+
+interface Reference {
+    id: Identifier
+    mode: "rw" | "r" | "w"
 }
 ```
 
 - This is mustaches or directive values.
 - If syntax errors exist, `expression` is `null` and `syntaxError` is an error object. Otherwise, `expression` is an [Expression] node and `syntaxError` is `null`.
+- `Reference` is objects but not `Node`. Those are external references which are in the expression.
 
 ## VDirectiveKey
 
@@ -138,10 +145,16 @@ interface VElement <: Node {
     startTag: VStartTag
     children: [ VText | VExpressionContainer | VElement ]
     endTag: VEndTag | null
+    variables: [ Variable ]
+}
+
+interface Variable {
+    id: Identifier
 }
 ```
 
-If `startTag.selfClosing` is `false` and `endTag` is `null`, the element does not have their end tag. E.g. `<li>Foo.`.
+- If `startTag.selfClosing` is `false` and `endTag` is `null`, the element does not have their end tag. E.g. `<li>Foo.`.
+- `Variable` is objects but not `Node`. Those are variable declarations that child elements can use. The elements which have [`v-for` directives] or a special attribute [scope] can declare variables.
 
 ## Program
 
@@ -161,3 +174,6 @@ This supports only HTML for now. However, I'm going to add other languages Vue.j
 [Literal]:    https://github.com/estree/estree/blob/master/es5.md#literal
 [Pattern]:    https://github.com/estree/estree/blob/master/es5.md#patterns
 [Identifier]: https://github.com/estree/estree/blob/master/es5.md#identifier
+
+[`v-for` directives]: https://vuejs.org/v2/guide/list.html#v-for
+[scope]:              https://vuejs.org/v2/guide/components.html#Scoped-Slots

lib/analyze-references.js

@@ -0,0 +1,44 @@
+/**
+ * @author Toru Nagashima <https://github.com/mysticatea>
+ * @copyright 2017 Toru Nagashima. All rights reserved.
+ * See LICENSE file in root directory for full license.
+ */
+"use strict"
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const ScopeAnalyzer = require("eslint-scope")
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+const OPTS = {ignoreEval: true, ecmaVersion: 8}
+
+/**
+ * Analyze the external references of the given AST.
+ * @param {ASTNode} ast The root node to analyze.
+ * @returns {Reference[]} The reference objects of external references.
+ */
+function analyzeReferences(ast) {
+    const result = ScopeAnalyzer.analyze(ast, OPTS)
+    const scope = result.acquire(ast)
+    const references = scope.through
+
+    return references.map(r => ({
+        id: r.identifier,
+        mode: (
+            r.isReadOnly() ? "r" :
+            r.isWriteOnly() ? "w" :
+            /* otherwise */ "rw"
+        ),
+    }))
+}
+
+//------------------------------------------------------------------------------
+// Exports
+//------------------------------------------------------------------------------
+
+module.exports = analyzeReferences

lib/script-parser.js

@@ -10,6 +10,7 @@
 //------------------------------------------------------------------------------
 
 const sortedIndexBy = require("lodash.sortedindexby")
+const analyzeReferences = require("./analyze-references")
 const decodeHtmlEntities = require("./decode-html-entities")
 const traverseNodes = require("./traverse-nodes")
 
@@ -66,13 +67,15 @@ function fixRangeAndLocByGap(node, tokenGenerator, gaps, codeStart) {
  * 1. Set `node.parent`.
  * 2. Fix `node.range` and `node.loc` for HTML entities.
  *
- * @param {ASTNode} ast The AST root node to initialize.
+ * @param {ASTNode} ast The AST root node to modify.
+ * @param {ASTNode[]} tokens The tokens to modify.
+ * @param {ASTNode[]} comments The comments to modify.
  * @param {TokenGenerator} tokenGenerator The token generator to calculate locations.
  * @param {(number[])[]} gaps The gaps to re-calculate locations.
  * @param {number} codeStart The start offset of the expression.
  * @returns {void}
  */
-function postprocess(ast, tokenGenerator, gaps, codeStart) {
+function postprocess(ast, tokens, comments, tokenGenerator, gaps, codeStart) {
     const gapsExist = gaps.length >= 1
 
     traverseNodes(ast, {
@@ -88,10 +91,10 @@ function postprocess(ast, tokenGenerator, gaps, codeStart) {
     })
 
     if (gapsExist) {
-        for (const token of ast.tokens) {
+        for (const token of tokens) {
             fixRangeAndLocByGap(token, tokenGenerator, gaps, codeStart)
         }
-        for (const comment of ast.comments) {
+        for (const comment of comments) {
             fixRangeAndLocByGap(comment, tokenGenerator, gaps, codeStart)
         }
     }
@@ -176,7 +179,7 @@ class ScriptParser {
      * @param {number} start The start offset to parse.
      * @param {number} end The end offset to parse.
      * @param {TokenGenerator} tokenGenerator The token generator to fix loc.
-     * @returns {ASTNode} The created AST node.
+     * @returns {{expression:ASTNode, tokens:ASTNode[], comments:ASTNode[], references:Reference[]}} The result of parsing.
      */
     parseExpression(start, end, tokenGenerator) {
         const codeStart = this.getInlineScriptStart(start)
@@ -207,15 +210,23 @@ class ScriptParser {
             )
         }
 
+        const references = analyzeReferences(ast)
         const expression = ast.body[0].expression
-        expression.tokens = ast.tokens || []
-        expression.comments = ast.comments || []
-        expression.tokens.shift()
-        expression.tokens.pop()
-
-        postprocess(expression, tokenGenerator, gaps, codeStart)
-
-        return expression
+        const tokens = ast.tokens || []
+        const comments = ast.comments || []
+        tokens.shift()
+        tokens.pop()
+
+        postprocess(
+            expression,
+            tokens,
+            comments,
+            tokenGenerator,
+            gaps,
+            codeStart
+        )
+
+        return {expression, tokens, comments, references}
     }
 }