initial commit

node_modules/tslint/lib/rules/preferForOfRule.js

@@ -0,0 +1,170 @@
+"use strict";
+/**
+ * @license
+ * Copyright 2018 Palantir Technologies, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+Object.defineProperty(exports, "__esModule", { value: true });
+var tslib_1 = require("tslib");
+var utils = require("tsutils");
+var ts = require("typescript");
+var Lint = require("../index");
+var utils_1 = require("../language/utils");
+var Rule = /** @class */ (function (_super) {
+    tslib_1.__extends(Rule, _super);
+    function Rule() {
+        return _super !== null && _super.apply(this, arguments) || this;
+    }
+    Rule.prototype.apply = function (sourceFile) {
+        return this.applyWithFunction(sourceFile, walk);
+    };
+    /* tslint:disable:object-literal-sort-keys */
+    Rule.metadata = {
+        ruleName: "prefer-for-of",
+        description: "Recommends a 'for-of' loop over a standard 'for' loop if the index is only used to access the array being iterated.",
+        rationale: "A for(... of ...) loop is easier to implement and read when the index is not needed.",
+        optionsDescription: "Not configurable.",
+        options: null,
+        optionExamples: [true],
+        type: "typescript",
+        typescriptOnly: false,
+    };
+    /* tslint:enable:object-literal-sort-keys */
+    Rule.FAILURE_STRING = "Expected a 'for-of' loop instead of a 'for' loop with this simple iteration";
+    return Rule;
+}(Lint.Rules.AbstractRule));
+exports.Rule = Rule;
+function walk(ctx) {
+    var sourceFile = ctx.sourceFile;
+    var variables;
+    return ts.forEachChild(sourceFile, function cb(node) {
+        if (utils.isForStatement(node)) {
+            visitForStatement(node);
+        }
+        return ts.forEachChild(node, cb);
+    });
+    function visitForStatement(node) {
+        var arrayNodeInfo = getForLoopHeaderInfo(node);
+        if (arrayNodeInfo === undefined) {
+            return;
+        }
+        var indexVariable = arrayNodeInfo.indexVariable, arrayExpr = arrayNodeInfo.arrayExpr;
+        if (variables === undefined) {
+            variables = utils.collectVariableUsage(sourceFile);
+        }
+        for (var _i = 0, _a = variables.get(indexVariable).uses; _i < _a.length; _i++) {
+            var location = _a[_i].location;
+            if (location.pos < node.initializer.end ||
+                location.pos >= node.end || // bail out on use outside of for loop
+                (location.pos >= node.statement.pos && // only check uses in loop body
+                    isNonSimpleIncrementorUse(location, arrayExpr, sourceFile))) {
+                return;
+            }
+        }
+        ctx.addFailure(node.getStart(sourceFile), node.statement.pos, Rule.FAILURE_STRING);
+    }
+}
+function isNonSimpleIncrementorUse(node, arrayExpr, sourceFile) {
+    // check if iterator is used for something other than reading data from array
+    var parent = node.parent;
+    return (!utils.isElementAccessExpression(parent) ||
+        // `a[i] = ...` or similar
+        utils.isReassignmentTarget(parent) ||
+        // `b[i]`
+        !nodeEquals(arrayExpr, utils_1.unwrapParentheses(parent.expression), sourceFile));
+}
+function nodeEquals(a, b, sourceFile) {
+    return a.getText(sourceFile) === b.getText(sourceFile);
+}
+// returns the iterator and array of a `for` loop if the `for` loop is basic.
+function getForLoopHeaderInfo(forLoop) {
+    var initializer = forLoop.initializer, condition = forLoop.condition, incrementor = forLoop.incrementor;
+    if (initializer === undefined || condition === undefined || incrementor === undefined) {
+        return undefined;
+    }
+    // Must start with `var i = 0;` or `let i = 0;`
+    if (!utils.isVariableDeclarationList(initializer) || initializer.declarations.length !== 1) {
+        return undefined;
+    }
+    var _a = initializer.declarations[0], indexVariable = _a.name, indexInit = _a.initializer;
+    if (indexVariable.kind !== ts.SyntaxKind.Identifier ||
+        indexInit === undefined ||
+        !isNumber(indexInit, "0")) {
+        return undefined;
+    }
+    // Must end with `i++`
+    if (!isIncremented(incrementor, indexVariable.text)) {
+        return undefined;
+    }
+    // Condition must be `i < arr.length;`
+    if (!utils.isBinaryExpression(condition)) {
+        return undefined;
+    }
+    var left = condition.left, operatorToken = condition.operatorToken, right = condition.right;
+    if (!isIdentifierNamed(left, indexVariable.text) ||
+        operatorToken.kind !== ts.SyntaxKind.LessThanToken ||
+        !utils.isPropertyAccessExpression(right)) {
+        return undefined;
+    }
+    var arrayExpr = right.expression, name = right.name;
+    if (name.text !== "length") {
+        return undefined;
+    }
+    return { indexVariable: indexVariable, arrayExpr: arrayExpr };
+}
+function isIncremented(node, indexVariableName) {
+    switch (node.kind) {
+        case ts.SyntaxKind.PrefixUnaryExpression:
+        case ts.SyntaxKind.PostfixUnaryExpression: {
+            var _a = node, operator = _a.operator, operand = _a.operand;
+            // `++x` or `x++`
+            return operator === ts.SyntaxKind.PlusPlusToken && isVar(operand);
+        }
+        case ts.SyntaxKind.BinaryExpression:
+            var _b = node, operatorToken = _b.operatorToken, updatedVar = _b.left, rhs = _b.right;
+            if (!isVar(updatedVar)) {
+                return false;
+            }
+            switch (operatorToken.kind) {
+                case ts.SyntaxKind.PlusEqualsToken:
+                    // x += 1
+                    return isOne(rhs);
+                case ts.SyntaxKind.EqualsToken: {
+                    if (!utils.isBinaryExpression(rhs)) {
+                        return false;
+                    }
+                    var rhsOp = rhs.operatorToken, left = rhs.left, right = rhs.right;
+                    // `x = 1 + x` or `x = x + 1`
+                    return (rhsOp.kind === ts.SyntaxKind.PlusToken &&
+                        ((isVar(left) && isOne(right)) || (isOne(left) && isVar(right))));
+                }
+                default:
+                    return false;
+            }
+        default:
+            return false;
+    }
+    function isVar(id) {
+        return isIdentifierNamed(id, indexVariableName);
+    }
+}
+function isIdentifierNamed(node, text) {
+    return utils.isIdentifier(node) && node.text === text;
+}
+function isOne(node) {
+    return isNumber(node, "1");
+}
+function isNumber(node, value) {
+    return utils.isNumericLiteral(node) && node.text === value;
+}