From 4de367417954b2198d52a986443cdcd9a89a57fb Mon Sep 17 00:00:00 2001
From: Anish Visaria <avisaria@hubspot.com>
Date: Fri, 9 Aug 2019 13:13:29 -0400
Subject: [PATCH] only include needed files

---
 src/app-error.ts | 25 +++++++++++++
 src/explore.ts   | 93 +++++++++++++++++++++++-------------------------
 src/index.ts     |  2 ++
 3 files changed, 72 insertions(+), 48 deletions(-)

diff --git a/src/app-error.ts b/src/app-error.ts
index 898b953..d44eb50 100644
--- a/src/app-error.ts
+++ b/src/app-error.ts
@@ -36,6 +36,19 @@ interface UnmappedBytesErrorContext {
   unmappedBytes: number;
 }
 
+interface InvalidMappingLineErrorContext {
+  code: 'InvalidMappingLine';
+  generatedLine: number;
+  maxLine: number;
+}
+
+interface InvalidMappingColumnErrorContext {
+  code: 'InvalidMappingColumn';
+  generatedLine: number;
+  generatedColumn: number;
+  maxColumn: number;
+}
+
 interface CannotOpenTempFileErrorContext {
   code: 'CannotOpenTempFile';
   error: Buffer;
@@ -46,6 +59,8 @@ export type ErrorContext =
   | CommonErrorContext
   | OneSourceSourceMapErrorContext
   | UnmappedBytesErrorContext
+  | InvalidMappingLineErrorContext
+  | InvalidMappingColumnErrorContext
   | CannotOpenTempFileErrorContext;
 
 export function getErrorMessage(context: ErrorContext): string {
@@ -71,6 +86,16 @@ See ${SOURCE_MAP_INFO_URL}`;
       return `Unable to map ${unmappedBytes}/${totalBytes} bytes (${bytesString}%)`;
     }
 
+    case 'InvalidMappingLine': {
+      const { generatedLine, maxLine } = context;
+      return `Your source map refers to generated line ${generatedLine}, but the source only contains ${maxLine} line(s).\nCheck that you are using the correct source map.`;
+    }
+
+    case 'InvalidMappingColumn': {
+      const { generatedLine, generatedColumn, maxColumn } = context;
+      return `Your source map refers to generated column ${generatedColumn} on line ${generatedLine}, but the source only contains ${maxColumn} column(s) on that line.\nCheck that you are using the correct source map.`;
+    }
+
     case 'CannotSaveFile':
       return 'Unable to save HTML to file';
 
diff --git a/src/explore.ts b/src/explore.ts
index fdf5948..ff046d2 100644
--- a/src/explore.ts
+++ b/src/explore.ts
@@ -21,7 +21,7 @@ export async function exploreBundle(
 
   const sourceMapData = await loadSourceMap(code, map);
 
-  const sizes = computeGeneratedFileSizes(sourceMapData);
+  const sizes = computeFileSizeMapOptimized(sourceMapData);
 
   const files = adjustSourcePaths(sizes.files, options);
 
@@ -85,26 +85,56 @@ async function loadSourceMap(codeFile: File, sourceMapFile?: File): Promise<Sour
   };
 }
 
-/** Calculate the number of bytes contributed by each source file */
-function computeGeneratedFileSizes(sourceMapData: SourceMapData): FileSizes {
-  const spans = computeSpans(sourceMapData);
-
+function computeFileSizeMapOptimized(sourceMapData: SourceMapData): FileSizes {
+  const { consumer, codeFileContent } = sourceMapData;
+  const lines = codeFileContent.split('\n');
   const files: FileSizeMap = {};
-  let unmappedBytes = 0;
-  let totalBytes = 0;
-
-  for (let i = 0; i < spans.length; i++) {
-    const { numChars, source } = spans[i];
+  let mappedBytes = 0;
+
+  consumer.computeColumnSpans();
+
+  consumer.eachMapping((m: any) => {
+    // lines are 1-based
+    const line = lines[m.generatedLine - 1];
+    if (line == null) {
+      throw new AppError({
+        code: 'InvalidMappingLine',
+        generatedLine: m.generatedLine,
+        maxLine: lines.length,
+      });
+    }
 
-    totalBytes += numChars;
+    // columns are 0-based
+    if (m.generatedColumn >= line.length) {
+      throw new AppError({
+        code: 'InvalidMappingColumn',
+        generatedLine: m.generatedLine,
+        generatedColumn: m.generatedColumn,
+        maxColumn: line.length,
+      });
+    }
 
-    if (source === null) {
-      unmappedBytes += numChars;
+    let mappingLength: number = 0;
+    if (m.lastGeneratedColumn != null) {
+      if (m.lastGeneratedColumn >= line.length) {
+        throw new AppError({
+          code: 'InvalidMappingColumn',
+          generatedLine: m.generatedLine,
+          generatedColumn: m.lastGeneratedColumn,
+          maxColumn: line.length,
+        });
+      }
+      mappingLength = m.lastGeneratedColumn - m.generatedColumn + 1;
     } else {
-      files[source] = (files[source] || 0) + numChars;
+      mappingLength = line.length - m.generatedColumn;
     }
-  }
+    files[m.source] = (files[m.source] || 0) + mappingLength;
+    mappedBytes += mappingLength;
+  });
 
+  // Doesn't count newlines as original version didn't count newlines
+  let totalBytes = codeFileContent.length - lines.length + 1;
+  const unmappedBytes = totalBytes - mappedBytes;
   return {
     files,
     unmappedBytes,
@@ -112,39 +142,6 @@ function computeGeneratedFileSizes(sourceMapData: SourceMapData): FileSizes {
   };
 }
 
-interface Span {
-  source: string | null;
-  numChars: number;
-}
-
-function computeSpans(sourceMapData: SourceMapData): Span[] {
-  const { consumer, codeFileContent } = sourceMapData;
-
-  const lines = codeFileContent.split('\n');
-  const spans: Span[] = [];
-  let numChars = 0;
-
-  let lastSource: string | null | undefined = undefined; // not a string, not null
-
-  for (let line = 1; line <= lines.length; line++) {
-    const lineText = lines[line - 1];
-    const numCols = lineText.length;
-
-    for (let column = 0; column < numCols; column++, numChars++) {
-      const { source } = consumer.originalPositionFor({ line, column });
-
-      if (source !== lastSource) {
-        lastSource = source;
-        spans.push({ source, numChars: 1 });
-      } else {
-        spans[spans.length - 1].numChars += 1;
-      }
-    }
-  }
-
-  return spans;
-}
-
 export function adjustSourcePaths(fileSizeMap: FileSizeMap, options: ExploreOptions): FileSizeMap {
   if (!options.noRoot) {
     const prefix = getCommonPathPrefix(Object.keys(fileSizeMap));
diff --git a/src/index.ts b/src/index.ts
index 414c8a7..242abe3 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -20,6 +20,8 @@ export type ErrorCode =
   | 'NoSourceMap'
   | 'OneSourceSourceMap'
   | 'UnmappedBytes'
+  | 'InvalidMappingLine'
+  | 'InvalidMappingColumn'
   | 'CannotSaveFile'
   | 'CannotCreateTempFile'
   | 'CannotOpenTempFile';