Add import-spacing rule

docs/_data/rules.json

@@ -247,6 +247,15 @@
     "type": "functionality",
     "typescriptOnly": false
   },
+  {
+    "ruleName": "import-spacing",
+    "description": "Ensures proper spacing between import statement keywords",
+    "optionsDescription": "",
+    "options": {},
+    "optionExamples": [],
+    "type": "style",
+    "typescriptOnly": false
+  },
   {
     "ruleName": "indent",
     "description": "Enforces indentation with tabs or spaces.",

docs/rules/import-spacing/index.html

@@ -0,0 +1,12 @@
+---
+ruleName: import-spacing
+description: Ensures proper spacing between import statement keywords
+optionsDescription: ''
+options: {}
+optionExamples: []
+type: style
+typescriptOnly: false
+layout: rule
+title: 'Rule: import-spacing'
+optionsJSON: '{}'
+---

src/rules/importSpacingRule.ts

@@ -0,0 +1,124 @@
+/**
+ * @license
+ * Copyright 2013 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.
+ */
+
+import * as ts from "typescript";
+
+import * as Lint from "../index";
+
+const LINE_BREAK_REGEX = /\n|\r\n/;
+
+export class Rule extends Lint.Rules.AbstractRule {
+    /* tslint:disable:object-literal-sort-keys */
+    public static metadata: Lint.IRuleMetadata = {
+        ruleName: "import-spacing",
+        description: "Ensures proper spacing between import statement keywords",
+        optionsDescription: "",
+        options: {},
+        optionExamples: [],
+        type: "style",
+        typescriptOnly: false,
+    };
+
+    public static ADD_SPACE_AFTER_IMPORT = "Add space after import";
+    public static TOO_MANY_SPACES_AFTER_IMPORT = "Too many spaces after import";
+    public static ADD_SPACE_AFTER_STAR = "Add space after *";
+    public static TOO_MANY_SPACES_AFTER_STAR = "Too many spaces after *";
+    public static ADD_SPACE_AFTER_FROM = "Add space after from";
+    public static TOO_MANY_SPACES_AFTER_FROM = "Too many spaces after from";
+    public static ADD_SPACE_BEFORE_FROM = "Add space before from";
+    public static TOO_MANY_SPACES_BEFORE_FROM = "Too many spaces before from";
+    public static NO_LINE_BREAKS = "No line breaks are allowed in import declaration";
+
+    public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
+        const comparisonWalker = new ImportStatementWalker(sourceFile, this.getOptions());
+        return this.applyWithWalker(comparisonWalker);
+    }
+}
+
+class ImportStatementWalker extends Lint.RuleWalker {
+    private static IMPORT_KEYWORD_LENGTH = 6; // "import".length;
+
+    public visitImportDeclaration(node: ts.ImportDeclaration) {
+        if (!node.importClause) {
+            this.checkModuleWithSideEffect(node);
+        } else {
+            const nodeStart = node.getStart();
+            const importKeywordEnd = node.getStart() + ImportStatementWalker.IMPORT_KEYWORD_LENGTH;
+            const moduleSpecifierStart = node.moduleSpecifier.getStart();
+            const importClauseEnd = node.importClause.getEnd();
+            const importClauseStart = node.importClause.getStart();
+
+            if (importKeywordEnd === importClauseStart) {
+                this.addFailure(this.createFailure(nodeStart, ImportStatementWalker.IMPORT_KEYWORD_LENGTH, Rule.ADD_SPACE_AFTER_IMPORT));
+            } else if (importClauseStart > (importKeywordEnd + 1)) {
+                this.addFailure(this.createFailure(nodeStart, importClauseStart - nodeStart, Rule.TOO_MANY_SPACES_AFTER_IMPORT));
+            }
+
+            const fromString = node.getText().substring(importClauseEnd - nodeStart, moduleSpecifierStart - nodeStart);
+
+            if (/from$/.test(fromString)) {
+                this.addFailure(this.createFailure(importClauseEnd, fromString.length, Rule.ADD_SPACE_AFTER_FROM));
+            }
+            if (/from\s{2,}$/.test(fromString)) {
+                this.addFailure(this.createFailure(importClauseEnd, fromString.length, Rule.TOO_MANY_SPACES_AFTER_FROM));
+            }
+            if (/^\s{2,}from/.test(fromString)) {
+                this.addFailure(this.createFailure(importClauseEnd, fromString.length, Rule.TOO_MANY_SPACES_BEFORE_FROM));
+            }
+            if (/^from/.test(fromString)) {
+                this.addFailure(this.createFailure(importClauseEnd, fromString.length, Rule.ADD_SPACE_BEFORE_FROM));
+            }
+
+            const text = node.getText();
+            const beforeImportClauseText = text.substring(0, importClauseStart - nodeStart);
+            const afterImportClauseText = text.substring(importClauseEnd - nodeStart);
+            if (LINE_BREAK_REGEX.test(beforeImportClauseText)) {
+                this.addFailure(this.createFailure(nodeStart, importClauseStart - nodeStart - 1, Rule.NO_LINE_BREAKS));
+            }
+            if (LINE_BREAK_REGEX.test(afterImportClauseText)) {
+                this.addFailure(this.createFailure(importClauseEnd, node.getEnd() - importClauseEnd, Rule.NO_LINE_BREAKS));
+            }
+        }
+        super.visitImportDeclaration(node);
+    }
+
+    public visitNamespaceImport(node: ts.NamespaceImport) {
+        const text = node.getText();
+        if (text.indexOf("*as") > -1) {
+            this.addFailure(this.createFailure(node.getStart(), node.getWidth(), Rule.ADD_SPACE_AFTER_STAR));
+        } else if (/\*\s{2,}as/.test(text)) {
+            this.addFailure(this.createFailure(node.getStart(), node.getWidth(), Rule.TOO_MANY_SPACES_AFTER_STAR));
+        } else if (LINE_BREAK_REGEX.test(text)) {
+            this.addFailure(this.createFailure(node.getStart(), node.getWidth(), Rule.NO_LINE_BREAKS));
+        }
+        super.visitNamespaceImport(node);
+    }
+
+    private checkModuleWithSideEffect(node: ts.ImportDeclaration) {
+        const moduleSpecifierStart = node.moduleSpecifier.getStart();
+        const nodeStart = node.getStart();
+        if ((nodeStart + ImportStatementWalker.IMPORT_KEYWORD_LENGTH + 1) < moduleSpecifierStart) {
+            this.addFailure(this.createFailure(nodeStart, moduleSpecifierStart - nodeStart, Rule.TOO_MANY_SPACES_AFTER_IMPORT));
+        }
+        if ((nodeStart + ImportStatementWalker.IMPORT_KEYWORD_LENGTH) === moduleSpecifierStart) {
+            this.addFailure(this.createFailure(nodeStart,  ImportStatementWalker.IMPORT_KEYWORD_LENGTH, Rule.ADD_SPACE_AFTER_IMPORT));
+        }
+        if (LINE_BREAK_REGEX.test(node.getText())) {
+            this.addFailure(this.createFailure(nodeStart, node.getWidth(), Rule.NO_LINE_BREAKS));
+        }
+    }
+}

test/rules/import-spacing/test.ts.lint

@@ -0,0 +1,157 @@
+// ---------------------------------------------------------------------------------------------------------------------
+// Module with side effect import
+// ---------------------------------------------------------------------------------------------------------------------
+// good
+import "styles.css";
+
+// bad
+import"styles.css";
+~~~~~~             [Add space after import]
+import  "styles.css";
+~~~~~~~~             [Too many spaces after import]
+import   "styles.css";
+~~~~~~~~~             [Too many spaces after import]
+
+import
+~~~~~~
+"styles.css";
+~~~~~~~~~~~~~ [No line breaks are allowed in import declaration]
+// ---------------------------------------------------------------------------------------------------------------------
+// Namespace import
+// ---------------------------------------------------------------------------------------------------------------------
+// good
+import * as ts from "typescript";
+
+// bad
+import*as ts from "typescript";
+~~~~~~                         [Add space after import]
+      ~~~~~~                   [Add space after *]
+import *as ts from "typescript";
+       ~~~~~~                   [Add space after *]
+import *  as ts from "typescript";
+       ~~~~~~~~                   [Too many spaces after *]
+import *   as ts from "typescript";
+       ~~~~~~~~~                   [Too many spaces after *]
+import* as ts from "typescript";
+~~~~~~                          [Add space after import]
+import * as ts from"typescript";
+              ~~~~~              [Add space after from]
+import  * as ts from "typescript";
+~~~~~~~~                          [Too many spaces after import]
+import    * as ts from "typescript";
+~~~~~~~~~~                          [Too many spaces after import]
+import * as ts from  "typescript";
+              ~~~~~~~               [Too many spaces after from]
+import
+~~~~~~ [No line breaks are allowed in import declaration]
+* as ts from "typescript";
+
+import *
+       ~
+as ts from "typescript";
+~~~~~                      [No line breaks are allowed in import declaration]
+
+import * as
+       ~~~~
+ts from "typescript";
+~~                   [No line breaks are allowed in import declaration]
+
+import * as ts
+              ~nil
+from "typescript";
+~~~~~~~~~~~~~~~~~~ [No line breaks are allowed in import declaration]
+
+
+// ---------------------------------------------------------------------------------------------------------------------
+// Single-line import
+// ---------------------------------------------------------------------------------------------------------------------
+// good
+import {Expression} from "typescript";
+
+// bad
+import{Expression}from"typescript";
+~~~~~~                             [Add space after import]
+                  ~~~~              [Add space after from]
+                  ~~~~              [Add space before from]
+import {Expression}from"typescript";
+                   ~~~~              [Add space after from]
+                   ~~~~              [Add space before from]
+import {Expression} from"typescript";
+                   ~~~~~             [Add space after from]
+import  {Expression} from "typescript";
+~~~~~~~~                               [Too many spaces after import]
+import {Expression}  from "typescript";
+                   ~~~~~~~             [Too many spaces before from]
+import {Expression} from  "typescript";
+                   ~~~~~~~              [Too many spaces after from]
+import  {Expression} from "typescript";
+~~~~~~~~                               [Too many spaces after import]
+import   {Expression} from "typescript";
+~~~~~~~~~                               [Too many spaces after import]
+
+import
+~~~~~~                         [No line breaks are allowed in import declaration]
+{Expression} from "typescript";
+
+import {Expression}
+                   ~nil
+from "typescript";
+~~~~~~~~~~~~~~~~~~ [No line breaks are allowed in import declaration]
+
+import {Expression} from
+                   ~~~~~
+"typescript";
+~~~~~~~~~~~~~ [No line breaks are allowed in import declaration]
+
+// ---------------------------------------------------------------------------------------------------------------------
+// Multi-line import
+// ---------------------------------------------------------------------------------------------------------------------
+// good
+import {
+    Expression
+} from "typescript";
+
+// bad
+import{
+~~~~~~  [Add space after import]
+    Expression
+} from "typescript";
+
+import {Expression
+}from "typescript";
+ ~~~~~                  [Add space before from]
+
+import {
+    Expression
+} from"typescript";
+ ~~~~~             [Add space after from]
+
+import  {
+~~~~~~~~  [Too many spaces after import]
+    Expression
+} from "typescript";
+
+import  {
+~~~~~~~~  [Too many spaces after import]
+    Expression
+} from "typescript";
+
+import {
+    Expression
+}
+ ~nil
+from "typescript";
+~~~~~~~~~~~~~~~~~~ [No line breaks are allowed in import declaration]
+
+import {
+    Expression
+} from
+ ~~~~~
+"typescript";
+~~~~~~~~~~~~~ [No line breaks are allowed in import declaration]
+
+import
+~~~~~~ [No line breaks are allowed in import declaration]
+{
+    Expression
+} from "typescript"

test/rules/import-spacing/tslint.json

@@ -0,0 +1,5 @@
+{
+    "rules": {
+        "import-spacing": true
+    }
+}