adding linebreak-style rule (palantir#1254)

fixes palantir#123

.gitattributes

@@ -3,3 +3,4 @@
 # being reported to be 1 character longer
 
 *.lint text eol=lf
+/test/rules/linebreak-style/**/CRLF/*.lint text eol=crlf

src/rules/linebreakStyleRule.ts

@@ -0,0 +1,48 @@
+import * as ts from "typescript";
+import * as Lint from "../lint";
+
+const OPTION_LINEBREAK_STYLE_CRLF = "CRLF";
+const OPTION_LINEBREAK_STYLE_LF = "LF";
+
+export class Rule extends Lint.Rules.AbstractRule {
+    public static FAILURE_STRINGS = {
+        CRLF: `Expected linebreak to be '${OPTION_LINEBREAK_STYLE_CRLF}'`,
+        LF: `Expected linebreak to be '${OPTION_LINEBREAK_STYLE_LF}'`,
+    };
+
+    public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
+        const failures = <Lint.RuleFailure[]>[];
+        const scanner = ts.createScanner(
+            sourceFile.languageVersion,
+            false,
+            sourceFile.languageVariant,
+            sourceFile.getFullText()
+        );
+
+        const linebreakStyle = this.getOptions().ruleArguments[0] || OPTION_LINEBREAK_STYLE_LF;
+        const expectLF = linebreakStyle === OPTION_LINEBREAK_STYLE_CRLF;
+        const expectedEOL = expectLF ? "\r\n" : "\n";
+        const failureString = expectLF ? Rule.FAILURE_STRINGS.CRLF : Rule.FAILURE_STRINGS.LF;
+
+        for (let token = scanner.scan(); token !== ts.SyntaxKind.EndOfFileToken; token = scanner.scan()) {
+            if (token === ts.SyntaxKind.NewLineTrivia) {
+                const text = scanner.getTokenText();
+                if (text !== expectedEOL) {
+                    failures.push(this.createFailure(sourceFile, scanner, failureString));
+                }
+            }
+        }
+
+        return failures;
+    }
+
+    public createFailure(sourceFile: ts.SourceFile, scanner: ts.Scanner, failure: string): Lint.RuleFailure {
+        // get the start of the current line
+        const start = sourceFile.getPositionOfLineAndCharacter(sourceFile.getLineAndCharacterOfPosition(scanner.getStartPos()).line, 0);
+        // since line endings are not visible, we simply end at the beginning of
+        // the line ending, which happens to be the start of the token.
+        const end = scanner.getStartPos();
+
+        return new Lint.RuleFailure(sourceFile, start, end, failure, this.getOptions().ruleName);
+    }
+}

src/tsconfig.json

@@ -73,6 +73,7 @@
         "rules/jsdocFormatRule.ts",
         "rules/labelPositionRule.ts",
         "rules/labelUndefinedRule.ts",
+        "rules/linebreakStyleRule.ts",
         "rules/maxLineLengthRule.ts",
         "rules/memberAccessRule.ts",
         "rules/memberOrderingRule.ts",

test/rules/linebreak-style/emptyFile/tslint.json

@@ -0,0 +1,5 @@
+{
+  "rules": {
+    "linebreak-style": [true, "LF"]
+  }
+}

test/rules/linebreak-style/failure/CRLF/test.ts.lint

@@ -0,0 +1,8 @@
+// this line uses CRLF
+~~~~~~~~~~~~~~~~~~~~~~ [Expected linebreak to be 'LF']
+// this line uses CRLF
+~~~~~~~~~~~~~~~~~~~~~~ [Expected linebreak to be 'LF']
+// this line uses CRLF
+~~~~~~~~~~~~~~~~~~~~~~ [Expected linebreak to be 'LF']
+// this line uses CRLF
+~~~~~~~~~~~~~~~~~~~~~~ [Expected linebreak to be 'LF']

test/rules/linebreak-style/failure/CRLF/tslint.json

@@ -0,0 +1,5 @@
+{
+  "rules": {
+    "linebreak-style": [true, "LF"]
+  }
+}

test/rules/linebreak-style/failure/LF/test.ts.lint

@@ -0,0 +1,8 @@
+// this line uses LF
+~~~~~~~~~~~~~~~~~~~~ [Expected linebreak to be 'CRLF']
+// this line uses LF
+~~~~~~~~~~~~~~~~~~~~ [Expected linebreak to be 'CRLF']
+// this line uses LF
+~~~~~~~~~~~~~~~~~~~~ [Expected linebreak to be 'CRLF']
+// this line uses LF
+~~~~~~~~~~~~~~~~~~~~ [Expected linebreak to be 'CRLF']

test/rules/linebreak-style/failure/LF/tslint.json

@@ -0,0 +1,5 @@
+{
+  "rules": {
+    "linebreak-style": [true, "CRLF"]
+  }
+}

test/rules/linebreak-style/success/CRLF/test.ts.lint

@@ -0,0 +1,4 @@
+// this line uses CRLF
+// this line uses CRLF
+// this line uses CRLF
+// this line uses CRLF

test/rules/linebreak-style/success/CRLF/tslint.json

@@ -0,0 +1,5 @@
+{
+  "rules": {
+    "linebreak-style": [true, "CRLF"]
+  }
+}

test/rules/linebreak-style/success/LF/test.ts.lint

@@ -0,0 +1,4 @@
+// this line uses LF
+// this line uses LF
+// this line uses LF
+// this line uses LF

test/rules/linebreak-style/success/LF/tslint.json

@@ -0,0 +1,5 @@
+{
+  "rules": {
+    "linebreak-style": [true, "LF"]
+  }
+}

test/tsconfig.json

@@ -70,6 +70,7 @@
         "../src/rules/jsdocFormatRule.ts",
         "../src/rules/labelPositionRule.ts",
         "../src/rules/labelUndefinedRule.ts",
+        "../src/rules/linebreakStyleRule.ts",
         "../src/rules/maxLineLengthRule.ts",
         "../src/rules/memberAccessRule.ts",
         "../src/rules/memberOrderingRule.ts",