Merge pull request #41 from hildjj/const

Move to using const wherever possible
peggyjs · Apr 16, 2021 · 2b2cf87 · 2b2cf87
2 parents e69be31 + 19bd44e
commit 2b2cf87
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Showing 31 changed files with 437 additions and 440 deletions.
diff --git a/.eslintrc.js b/.eslintrc.js
@@ -627,10 +627,7 @@ module.exports = {
     // allow to make exceptions for these cases.
     "prefer-arrow-callback": "off",
 
-    // Disabled because using `const` for anything else than for immutable
-    // variables of permanent character (generally spelled in `ALL_CAPS`) feels
-    // confusing.
-    "prefer-const": "off",
+    "prefer-const": "error",
 
     "prefer-numeric-literals": "error",
 

diff --git a/benchmark/benchmarks.js b/benchmark/benchmarks.js
@@ -1,6 +1,6 @@
 "use strict";
 
-let benchmarks = [
+const benchmarks = [
   {
     id: "json",
     title: "JSON",

diff --git a/benchmark/index.js b/benchmark/index.js
@@ -2,13 +2,13 @@
 
 /* eslint-env browser, jquery */
 
-let Runner = require("./runner.js");
-let benchmarks = require("./benchmarks.js");
+const Runner = require("./runner.js");
+const benchmarks = require("./benchmarks.js");
 
 $("#run").click(() => {
   // Results Table Manipulation
 
-  let resultsTable = $("#results-table");
+  const resultsTable = $("#results-table");
 
   function appendHeading(heading) {
     resultsTable.append(
@@ -60,8 +60,8 @@ $("#run").click(() => {
   //
   //   2. To minimize random errors.
 
-  let runCount = parseInt($("#run-count").val(), 10);
-  let options = {
+  const runCount = parseInt($("#run-count").val(), 10);
+  const options = {
     cache: $("#cache").is(":checked"),
     optimize: $("#optimize").val()
   };

diff --git a/benchmark/runner.js b/benchmark/runner.js
@@ -1,12 +1,12 @@
 "use strict";
 
-let peg = require("../lib/peg");
+const peg = require("../lib/peg");
 
-let Runner = {
+const Runner = {
   run(benchmarks, runCount, options, callbacks) {
     // Queue
 
-    let Q = {
+    const Q = {
       functions: [],
 
       add(f) {
@@ -37,7 +37,7 @@ let Runner = {
     // The enqueued functions share state, which is all stored in the properties
     // of the |state| object.
 
-    let state = {};
+    const state = {};
 
     function initialize() {
       callbacks.start();
@@ -63,15 +63,15 @@ let Runner = {
       return function() {
         callbacks.testStart(benchmark, test);
 
-        let input = callbacks.readFile(benchmark.id + "/" + test.file);
+        const input = callbacks.readFile(benchmark.id + "/" + test.file);
 
         let parseTime = 0;
         for (let i = 0; i < runCount; i++) {
-          let t = (new Date()).getTime();
+          const t = (new Date()).getTime();
           state.parser.parse(input);
           parseTime += (new Date()).getTime() - t;
         }
-        let averageParseTime = parseTime / runCount;
+        const averageParseTime = parseTime / runCount;
 
         callbacks.testFinish(benchmark, test, input.length, averageParseTime);
 

diff --git a/lib/compiler/asts.js b/lib/compiler/asts.js
@@ -1,9 +1,9 @@
 "use strict";
 
-let visitor = require("./visitor");
+const visitor = require("./visitor");
 
 // AST utilities.
-let asts = {
+const asts = {
   findRule(ast, name) {
     for (let i = 0; i < ast.rules.length; i++) {
       if (ast.rules[i].name === name) {
@@ -32,7 +32,7 @@ let asts = {
       return consumes(node.expression);
     }
 
-    let consumes = visitor.build({
+    const consumes = visitor.build({
       rule: consumesExpression,
       named: consumesExpression,
 

diff --git a/lib/compiler/index.js b/lib/compiler/index.js
@@ -1,17 +1,17 @@
 "use strict";
 
-let generateBytecode = require("./passes/generate-bytecode");
-let generateJS = require("./passes/generate-js");
-let removeProxyRules = require("./passes/remove-proxy-rules");
-let reportDuplicateLabels = require("./passes/report-duplicate-labels");
-let reportDuplicateRules = require("./passes/report-duplicate-rules");
-let reportInfiniteRecursion = require("./passes/report-infinite-recursion");
-let reportInfiniteRepetition = require("./passes/report-infinite-repetition");
-let reportUndefinedRules = require("./passes/report-undefined-rules");
-let visitor = require("./visitor");
+const generateBytecode = require("./passes/generate-bytecode");
+const generateJS = require("./passes/generate-js");
+const removeProxyRules = require("./passes/remove-proxy-rules");
+const reportDuplicateLabels = require("./passes/report-duplicate-labels");
+const reportDuplicateRules = require("./passes/report-duplicate-rules");
+const reportInfiniteRecursion = require("./passes/report-infinite-recursion");
+const reportInfiniteRepetition = require("./passes/report-infinite-repetition");
+const reportUndefinedRules = require("./passes/report-undefined-rules");
+const visitor = require("./visitor");
 
 function processOptions(options, defaults) {
-  let processedOptions = {};
+  const processedOptions = {};
 
   Object.keys(options).forEach(name => {
     processedOptions[name] = options[name];
@@ -26,7 +26,7 @@ function processOptions(options, defaults) {
   return processedOptions;
 }
 
-let compiler = {
+const compiler = {
   // AST node visitor builder. Useful mainly for plugins which manipulate the
   // AST.
   visitor: visitor,

diff --git a/lib/compiler/js.js b/lib/compiler/js.js
@@ -3,7 +3,7 @@
 function hex(ch) { return ch.charCodeAt(0).toString(16).toUpperCase(); }
 
 // JavaScript code generation helpers.
-let js = {
+const js = {
   stringEscape(s) {
     // ECMA-262, 5th ed., 7.8.4: All characters may appear literally in a string
     // literal except for the closing quote character, backslash, carriage

diff --git a/lib/compiler/opcodes.js b/lib/compiler/opcodes.js
@@ -1,7 +1,7 @@
 "use strict";
 
 // Bytecode instruction opcodes.
-let opcodes = {
+const opcodes = {
   // Stack Manipulation
 
   PUSH:             0,    // PUSH c

diff --git a/lib/compiler/passes/generate-bytecode.js b/lib/compiler/passes/generate-bytecode.js
@@ -1,9 +1,9 @@
 "use strict";
 
-let asts = require("../asts");
-let js = require("../js");
-let op = require("../opcodes");
-let visitor = require("../visitor");
+const asts = require("../asts");
+const js = require("../js");
+const op = require("../opcodes");
+const visitor = require("../visitor");
 
 // Generates bytecode.
 //
@@ -188,10 +188,10 @@ let visitor = require("../visitor");
 //
 //        silentFails--;
 function generateBytecode(ast) {
-  let consts = [];
+  const consts = [];
 
   function addConst(value) {
-    let index = consts.indexOf(value);
+    const index = consts.indexOf(value);
 
     return index === -1 ? consts.push(value) - 1 : index;
   }
@@ -203,7 +203,7 @@ function generateBytecode(ast) {
   }
 
   function cloneEnv(env) {
-    let clone = {};
+    const clone = {};
 
     Object.keys(env).forEach(name => {
       clone[name] = env[name];
@@ -229,7 +229,7 @@ function generateBytecode(ast) {
   }
 
   function buildCall(functionIndex, delta, env, sp) {
-    let params = Object.keys(env).map(name => sp - env[name]);
+    const params = Object.keys(env).map(name => sp - env[name]);
 
     return [op.CALL, functionIndex, delta, params.length].concat(params);
   }
@@ -261,7 +261,7 @@ function generateBytecode(ast) {
   }
 
   function buildSemanticPredicate(code, negative, context) {
-    let functionIndex = addFunctionConst(Object.keys(context.env), code);
+    const functionIndex = addFunctionConst(Object.keys(context.env), code);
 
     return buildSequence(
       [op.UPDATE_SAVED_POS],
@@ -287,7 +287,7 @@ function generateBytecode(ast) {
     );
   }
 
-  let generate = visitor.build({
+  const generate = visitor.build({
     grammar(node) {
       node.rules.forEach(generate);
 
@@ -303,7 +303,7 @@ function generateBytecode(ast) {
     },
 
     named(node, context) {
-      let nameIndex = addConst(
+      const nameIndex = addConst(
         "peg$otherExpectation(\"" + js.stringEscape(node.name) + "\")"
       );
 
@@ -344,15 +344,15 @@ function generateBytecode(ast) {
     },
 
     action(node, context) {
-      let env = cloneEnv(context.env);
-      let emitCall = node.expression.type !== "sequence"
+      const env = cloneEnv(context.env);
+      const emitCall = node.expression.type !== "sequence"
                   || node.expression.elements.length === 0;
-      let expressionCode = generate(node.expression, {
+      const expressionCode = generate(node.expression, {
         sp: context.sp + (emitCall ? 1 : 0),
         env: env,
         action: node
       });
-      let functionIndex = addFunctionConst(Object.keys(env), node.code);
+      const functionIndex = addFunctionConst(Object.keys(env), node.code);
 
       return emitCall
         ? buildSequence(
@@ -374,7 +374,8 @@ function generateBytecode(ast) {
     sequence(node, context) {
       function buildElementsCode(elements, context) {
         if (elements.length > 0) {
-          let processedCount = node.elements.length - elements.slice(1).length;
+          const processedCount
+            = node.elements.length - elements.slice(1).length;
 
           return buildSequence(
             generate(elements[0], {
@@ -398,7 +399,7 @@ function generateBytecode(ast) {
           );
         } else {
           if (context.action) {
-            let functionIndex = addFunctionConst(
+            const functionIndex = addFunctionConst(
               Object.keys(context.env),
               context.action.code
             );
@@ -430,7 +431,7 @@ function generateBytecode(ast) {
     },
 
     labeled(node, context) {
-      let env = cloneEnv(context.env);
+      const env = cloneEnv(context.env);
 
       context.env[node.label] = context.sp + 1;
 
@@ -481,7 +482,7 @@ function generateBytecode(ast) {
     },
 
     zero_or_more(node, context) {
-      let expressionCode = generate(node.expression, {
+      const expressionCode = generate(node.expression, {
         sp: context.sp + 1,
         env: cloneEnv(context.env),
         action: null
@@ -496,7 +497,7 @@ function generateBytecode(ast) {
     },
 
     one_or_more(node, context) {
-      let expressionCode = generate(node.expression, {
+      const expressionCode = generate(node.expression, {
         sp: context.sp + 1,
         env: cloneEnv(context.env),
         action: null
@@ -535,13 +536,13 @@ function generateBytecode(ast) {
 
     literal(node) {
       if (node.value.length > 0) {
-        let stringIndex = addConst("\""
+        const stringIndex = addConst("\""
           + js.stringEscape(
               node.ignoreCase ? node.value.toLowerCase() : node.value
             )
           + "\""
         );
-        let expectedIndex = addConst(
+        const expectedIndex = addConst(
           "peg$literalExpectation("
             + "\"" + js.stringEscape(node.value) + "\", "
             + node.ignoreCase
@@ -561,14 +562,14 @@ function generateBytecode(ast) {
           [op.FAIL, expectedIndex]
         );
       } else {
-        let stringIndex = addConst("\"\"");
+        const stringIndex = addConst("\"\"");
 
         return [op.PUSH, stringIndex];
       }
     },
 
     class(node) {
-      let regexp = "/^["
+      const regexp = "/^["
         + (node.inverted ? "^" : "")
         + node.parts.map(part =>
             Array.isArray(part)
@@ -578,15 +579,15 @@ function generateBytecode(ast) {
               : js.regexpClassEscape(part)
           ).join("")
         + "]/" + (node.ignoreCase ? "i" : "");
-      let parts = "["
+      const parts = "["
         + node.parts.map(part =>
             Array.isArray(part)
               ? "[\"" + js.stringEscape(part[0]) + "\", \"" + js.stringEscape(part[1]) + "\"]"
               : "\"" + js.stringEscape(part) + "\""
           ).join(", ")
         + "]";
-      let regexpIndex = addConst(regexp);
-      let expectedIndex = addConst(
+      const regexpIndex = addConst(regexp);
+      const expectedIndex = addConst(
         "peg$classExpectation("
           + parts + ", "
           + node.inverted + ", "
@@ -602,7 +603,7 @@ function generateBytecode(ast) {
     },
 
     any() {
-      let expectedIndex = addConst("peg$anyExpectation()");
+      const expectedIndex = addConst("peg$anyExpectation()");
 
       return buildCondition(
         [op.MATCH_ANY],