Give some love to the linter

lib/lint/src/formatters/asFormatter.ts

@@ -0,0 +1,56 @@
+import { AbstractFormatter } from "tslint/lib/language/formatter/abstractFormatter";
+import { IFormatterMetadata } from "tslint/lib/language/formatter/formatter";
+import { RuleFailure } from "tslint/lib/language/rule/rule";
+
+const colorBlue: string = "\u001b[93m";
+const colorYellow: string = "\u001b[93m";
+const colorRed: string = "\u001b[91m";
+const colorReset: string = "\u001b[0m";
+
+export class Formatter extends AbstractFormatter {
+
+  static metadata: IFormatterMetadata = {
+    formatterName: "as",
+    description: "AssemblyScript's TSLint formatter.",
+    sample: "Similar to ASC's output.",
+    consumer: "human",
+  };
+
+  lastSeverity: string;
+  lastFailure: string;
+
+  format(failures: RuleFailure[]): string {
+    return `${this.mapToMessages(failures).join("\n")}\n`;
+  }
+
+  mapToMessages(failures: RuleFailure[]): string[] {
+    return failures.map((failure: RuleFailure) => {
+      var fileName = failure.getFileName();
+      var failureString = failure.getFailure();
+      var ruleName = failure.getRuleName();
+      var lineAndCharacter = failure.getStartPosition().getLineAndCharacter();
+      var positionTuple = `:${lineAndCharacter.line + 1}:${lineAndCharacter.character + 1}`;
+      if (this.lastSeverity == failure.getRuleSeverity() && this.lastFailure == failureString) {
+        return "  in " + fileName + positionTuple;
+      } else {
+        let message = this.lastSeverity ? "\n" : "";
+        switch (this.lastSeverity = failure.getRuleSeverity()) {
+          case "warning": {
+            message += colorYellow + "WARNING:" + colorReset;
+            break;
+          }
+          case "error": {
+            message += colorRed + "ERROR:" + colorReset;
+            break;
+          }
+          default: {
+            message += failure.getRuleSeverity();
+            break;
+          }
+        }
+        this.lastFailure = failureString;
+        return message + " " + failureString + " [" + ruleName + "]\n  in " + fileName + positionTuple;
+      }
+    });
+  }
+}