feat(#455): improve error logging inside of expressions (#476)

packages/astro/src/compiler/codegen/index.ts

@@ -13,7 +13,7 @@ import _babelGenerator from '@babel/generator';
 import babelParser from '@babel/parser';
 import { codeFrameColumns } from '@babel/code-frame';
 import * as babelTraverse from '@babel/traverse';
-import { error, warn } from '../../logger.js';
+import { error, warn, parseError } from '../../logger.js';
 import { fetchContent } from './content.js';
 import { isFetchContent } from './utils.js';
 import { yellow } from 'kleur/colors';
@@ -21,6 +21,8 @@ import { isComponentTag } from '../utils';
 import { renderMarkdown } from '@astrojs/markdown-support';
 import { transform } from '../transform/index.js';
 import { PRISM_IMPORT } from '../transform/prism.js';
+import { positionAt } from '../utils';
+import { readFileSync } from 'fs';
 
 const traverse: typeof babelTraverse.default = (babelTraverse.default as any).default;
 
@@ -170,14 +172,38 @@ function getComponentWrapper(_name: string, { url, importSpecifier }: ComponentI
 }
 
 /** Evaluate expression (safely) */
-function compileExpressionSafe(raw: string): string {
+function compileExpressionSafe(raw: string, { state, compileOptions, location }: { state: CodegenState, compileOptions: CompileOptions, location: { start: number, end: number } }): string|null {
+  try {
     let { code } = transformSync(raw, {
       loader: 'tsx',
       jsxFactory: 'h',
       jsxFragment: 'Fragment',
-    charset: 'utf8',
+      charset: 'utf8'
     });
     return code;
+  } catch ({ errors }) {
+    const err = new Error() as any;
+    const e = errors[0];
+    err.filename = state.filename;
+    const text = readFileSync(state.filename).toString();
+    const start = positionAt(location.start, text);
+    start.line += e.location.line;
+    start.character += e.location.column + 1;
+    err.start = { line: start.line, column: start.character };
+
+    const end = { ...start };
+    end.character += e.location.length;
+
+    const frame = codeFrameColumns(text, {
+      start: { line: start.line, column: start.character },
+      end: { line: end.line, column: end.character },
+    })
+
+    err.frame = frame;
+    err.message = e.text;
+    parseError(compileOptions.logging, err);
+    return null;
+  }
 }
 
 interface CompileResult {
@@ -473,8 +499,11 @@ async function compileHtml(enterNode: TemplateNode, state: CodegenState, compile
                 raw += children[nextChildIndex++];
               }
             }
+            const location = { start: node.start, end: node.end };
             // TODO Do we need to compile this now, or should we compile the entire module at the end?
-            let code = compileExpressionSafe(raw).trim().replace(/\;$/, '');
+            let code = compileExpressionSafe(raw, { state, compileOptions, location });
+            if (code === null) throw new Error(`Unable to compile expression`);
+            code = code.trim().replace(/\;$/, '');
             if (!FALSY_EXPRESSIONS.has(code)) {
               if (state.markers.insideMarkdown) {
                 buffers[curr] += `{${code}}`;

packages/astro/src/compiler/utils.ts

@@ -2,3 +2,87 @@
 export function isComponentTag(tag: string) {
   return /^[A-Z]/.test(tag) || /^[a-z]+\./.test(tag);
 }
+
+export interface Position {
+  line: number;
+  character: number;
+}
+
+/** Clamps a number between min and max */
+export function clamp(num: number, min: number, max: number): number {
+  return Math.max(min, Math.min(max, num));
+}
+
+/**
+ * Get the line and character based on the offset
+ * @param offset The index of the position
+ * @param text The text for which the position should be retrived
+ */
+export function positionAt(offset: number, text: string): Position {
+  offset = clamp(offset, 0, text.length);
+
+  const lineOffsets = getLineOffsets(text);
+  let low = 0;
+  let high = lineOffsets.length;
+  if (high === 0) {
+    return { line: 0, character: offset };
+  }
+
+  while (low < high) {
+    const mid = Math.floor((low + high) / 2);
+    if (lineOffsets[mid] > offset) {
+      high = mid;
+    } else {
+      low = mid + 1;
+    }
+  }
+
+  // low is the least x for which the line offset is larger than the current offset
+  // or array.length if no line offset is larger than the current offset
+  const line = low - 1;
+  return { line, character: offset - lineOffsets[line] };
+}
+
+/**
+ * Get the offset of the line and character position
+ * @param position Line and character position
+ * @param text The text for which the offset should be retrived
+ */
+export function offsetAt(position: Position, text: string): number {
+  const lineOffsets = getLineOffsets(text);
+
+  if (position.line >= lineOffsets.length) {
+    return text.length;
+  } else if (position.line < 0) {
+    return 0;
+  }
+
+  const lineOffset = lineOffsets[position.line];
+  const nextLineOffset = position.line + 1 < lineOffsets.length ? lineOffsets[position.line + 1] : text.length;
+
+  return clamp(nextLineOffset, lineOffset, lineOffset + position.character);
+}
+
+/** Get the offset of all lines */
+function getLineOffsets(text: string) {
+  const lineOffsets = [];
+  let isLineStart = true;
+
+  for (let i = 0; i < text.length; i++) {
+    if (isLineStart) {
+      lineOffsets.push(i);
+      isLineStart = false;
+    }
+    const ch = text.charAt(i);
+    isLineStart = ch === '\r' || ch === '\n';
+    if (ch === '\r' && i + 1 < text.length && text.charAt(i + 1) === '\n') {
+      i++;
+    }
+  }
+
+  if (isLineStart && text.length > 0) {
+    lineOffsets.push(text.length);
+  }
+
+  return lineOffsets;
+}