1 files changed, 160 insertions, 0 deletions
diff --git a/cli/js/diagnostics_util.ts b/cli/js/diagnostics_util.ts
new file mode 100644
index 000000000..cc384ebb0
--- /dev/null
+++ b/cli/js/diagnostics_util.ts
@@ -0,0 +1,160 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+// These utilities are used by compiler.ts to format TypeScript diagnostics
+// into Deno Diagnostics.
+
+import {
+  Diagnostic,
+  DiagnosticCategory,
+  DiagnosticMessageChain,
+  DiagnosticItem
+} from "./diagnostics.ts";
+
+interface SourceInformation {
+  sourceLine: string;
+  lineNumber: number;
+  scriptResourceName: string;
+  startColumn: number;
+  endColumn: number;
+}
+
+function fromDiagnosticCategory(
+  category: ts.DiagnosticCategory
+): DiagnosticCategory {
+  switch (category) {
+    case ts.DiagnosticCategory.Error:
+      return DiagnosticCategory.Error;
+    case ts.DiagnosticCategory.Message:
+      return DiagnosticCategory.Info;
+    case ts.DiagnosticCategory.Suggestion:
+      return DiagnosticCategory.Suggestion;
+    case ts.DiagnosticCategory.Warning:
+      return DiagnosticCategory.Warning;
+    default:
+      throw new Error(
+        `Unexpected DiagnosticCategory: "${category}"/"${ts.DiagnosticCategory[category]}"`
+      );
+  }
+}
+
+function getSourceInformation(
+  sourceFile: ts.SourceFile,
+  start: number,
+  length: number
+): SourceInformation {
+  const scriptResourceName = sourceFile.fileName;
+  const {
+    line: lineNumber,
+    character: startColumn
+  } = sourceFile.getLineAndCharacterOfPosition(start);
+  const endPosition = sourceFile.getLineAndCharacterOfPosition(start + length);
+  const endColumn =
+    lineNumber === endPosition.line ? endPosition.character : startColumn;
+  const lastLineInFile = sourceFile.getLineAndCharacterOfPosition(
+    sourceFile.text.length
+  ).line;
+  const lineStart = sourceFile.getPositionOfLineAndCharacter(lineNumber, 0);
+  const lineEnd =
+    lineNumber < lastLineInFile
+      ? sourceFile.getPositionOfLineAndCharacter(lineNumber + 1, 0)
+      : sourceFile.text.length;
+  const sourceLine = sourceFile.text
+    .slice(lineStart, lineEnd)
+    .replace(/\s+$/g, "")
+    .replace("\t", " ");
+  return {
+    sourceLine,
+    lineNumber,
+    scriptResourceName,
+    startColumn,
+    endColumn
+  };
+}
+
+/** Converts a TypeScript diagnostic message chain to a Deno one. */
+function fromDiagnosticMessageChain(
+  messageChain: ts.DiagnosticMessageChain[] | undefined
+): DiagnosticMessageChain[] | undefined {
+  if (!messageChain) {
+    return undefined;
+  }
+
+  return messageChain.map(({ messageText: message, code, category, next }) => {
+    return {
+      message,
+      code,
+      category: fromDiagnosticCategory(category),
+      next: fromDiagnosticMessageChain(next)
+    };
+  });
+}
+
+/** Parse out information from a TypeScript diagnostic structure. */
+function parseDiagnostic(
+  item: ts.Diagnostic | ts.DiagnosticRelatedInformation
+): DiagnosticItem {
+  const {
+    messageText,
+    category: sourceCategory,
+    code,
+    file,
+    start: startPosition,
+    length
+  } = item;
+  const sourceInfo =
+    file && startPosition && length
+      ? getSourceInformation(file, startPosition, length)
+      : undefined;
+  const endPosition =
+    startPosition && length ? startPosition + length : undefined;
+  const category = fromDiagnosticCategory(sourceCategory);
+
+  let message: string;
+  let messageChain: DiagnosticMessageChain | undefined;
+  if (typeof messageText === "string") {
+    message = messageText;
+  } else {
+    message = messageText.messageText;
+    messageChain = fromDiagnosticMessageChain([messageText])![0];
+  }
+
+  const base = {
+    message,
+    messageChain,
+    code,
+    category,
+    startPosition,
+    endPosition
+  };
+
+  return sourceInfo ? { ...base, ...sourceInfo } : base;
+}
+
+/** Convert a diagnostic related information array into a Deno diagnostic
+ * array. */
+function parseRelatedInformation(
+  relatedInformation: readonly ts.DiagnosticRelatedInformation[]
+): DiagnosticItem[] {
+  const result: DiagnosticItem[] = [];
+  for (const item of relatedInformation) {
+    result.push(parseDiagnostic(item));
+  }
+  return result;
+}
+
+/** Convert TypeScript diagnostics to Deno diagnostics. */
+export function fromTypeScriptDiagnostic(
+  diagnostics: readonly ts.Diagnostic[]
+): Diagnostic {
+  const items: DiagnosticItem[] = [];
+  for (const sourceDiagnostic of diagnostics) {
+    const item: DiagnosticItem = parseDiagnostic(sourceDiagnostic);
+    if (sourceDiagnostic.relatedInformation) {
+      item.relatedInformation = parseRelatedInformation(
+        sourceDiagnostic.relatedInformation
+      );
+    }
+    items.push(item);
+  }
+  return { items };
+}