Move VLQ out of strings

jridgewell · Jun 27, 2024 · ed80f4c · ed80f4c
1 parent e86a0ff
commit ed80f4c
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Showing 4 changed files with 27 additions and 19 deletions.
diff --git a/src/scopes.ts b/src/scopes.ts
@@ -1,5 +1,5 @@
-import { StringReader, StringWriter, comma, semicolon } from './strings';
-import { decodeInteger, encodeInteger } from './vlq';
+import { StringReader, StringWriter } from './strings';
+import { comma, decodeInteger, encodeInteger, hasMoreVlq, semicolon } from './vlq';
 
 type Line = number;
 type Column = number;
@@ -40,7 +40,7 @@ export function decodeOriginalScopes(input: string): OriginalScope[] {
     line = decodeInteger(reader, line);
     const column = decodeInteger(reader, 0);
 
-    if (!reader.hasMoreVlq(length)) {
+    if (!hasMoreVlq(reader, length)) {
       const last = stack.pop()!;
       last[2] = line;
       last[3] = column;
@@ -56,13 +56,13 @@ export function decodeOriginalScopes(input: string): OriginalScope[] {
     scopes.push(scope);
     stack.push(scope);
 
-    if (reader.hasMoreVlq(length)) {
+    if (hasMoreVlq(reader, length)) {
       const vars: Var[] = [];
       scope.vars = vars;
       do {
         const varsIndex = decodeInteger(reader, 0);
         vars.push(varsIndex);
-      } while (reader.hasMoreVlq(length));
+      } while (hasMoreVlq(reader, length));
     }
   }
 
@@ -146,7 +146,7 @@ export function decodeGeneratedRanges(input: string): GeneratedRange[] {
     for (; reader.pos < semi; reader.pos++) {
       genColumn = decodeInteger(reader, genColumn);
 
-      if (!reader.hasMoreVlq(semi)) {
+      if (!hasMoreVlq(reader, semi)) {
         const range = stack.pop()!;
         range[2] = genLine;
         range[3] = genColumn;
@@ -190,7 +190,7 @@ export function decodeGeneratedRanges(input: string): GeneratedRange[] {
         range.isScope = true;
       }
 
-      if (reader.hasMoreVlq(semi)) {
+      if (hasMoreVlq(reader, semi)) {
         const bindings: ExpressionBinding[][] = [];
         range.bindings = bindings;
         do {
@@ -211,7 +211,7 @@ export function decodeGeneratedRanges(input: string): GeneratedRange[] {
             expressionRanges = [[expressionsCount]];
           }
           bindings.push(expressionRanges);
-        } while (reader.hasMoreVlq(semi));
+        } while (hasMoreVlq(reader, semi));
       }
 
       ranges.push(range);
@@ -220,7 +220,7 @@ export function decodeGeneratedRanges(input: string): GeneratedRange[] {
 
     genLine++;
     reader.pos = semi + 1;
-  } while (reader.pos < input.length);
+  } while (reader.hasMore());
 
   return ranges;
 }

diff --git a/src/sourcemap-codec.ts b/src/sourcemap-codec.ts
@@ -1,5 +1,5 @@
-import { decodeInteger, encodeInteger } from './vlq';
-import { StringWriter, StringReader, comma, semicolon } from './strings';
+import { comma, decodeInteger, encodeInteger, hasMoreVlq, semicolon } from './vlq';
+import { StringWriter, StringReader } from './strings';
 
 export {
   decodeOriginalScopes,
@@ -39,12 +39,12 @@ export function decode(mappings: string): SourceMapMappings {
       if (genColumn < lastCol) sorted = false;
       lastCol = genColumn;
 
-      if (reader.hasMoreVlq(semi)) {
+      if (hasMoreVlq(reader, semi)) {
         sourcesIndex = decodeInteger(reader, sourcesIndex);
         sourceLine = decodeInteger(reader, sourceLine);
         sourceColumn = decodeInteger(reader, sourceColumn);
 
-        if (reader.hasMoreVlq(semi)) {
+        if (hasMoreVlq(reader, semi)) {
           namesIndex = decodeInteger(reader, namesIndex);
           seg = [genColumn, sourcesIndex, sourceLine, sourceColumn, namesIndex];
         } else {

diff --git a/src/strings.ts b/src/strings.ts
@@ -1,6 +1,4 @@
 const bufLength = 1024 * 16;
-export const comma = ','.charCodeAt(0);
-export const semicolon = ';'.charCodeAt(0);
 
 // Provide a fallback for older environments.
 const td =
@@ -55,10 +53,12 @@ export class StringReader {
     return this.buffer.charCodeAt(this.pos++);
   }
 
-  hasMoreVlq(max: number): boolean {
-    const { buffer, pos } = this;
-    if (pos >= max) return false;
-    return buffer.charCodeAt(pos) !== comma;
+  peek(): number {
+    return this.buffer.charCodeAt(this.pos);
+  }
+
+  hasMore(): boolean {
+    return this.pos < this.buffer.length;
   }
 
   indexOf(char: string): number {

diff --git a/src/vlq.ts b/src/vlq.ts
@@ -1,5 +1,8 @@
 import type { StringReader, StringWriter } from './strings';
 
+export const comma = ','.charCodeAt(0);
+export const semicolon = ';'.charCodeAt(0);
+
 const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
 const intToChar = new Uint8Array(64); // 64 possible chars.
 const charToInt = new Uint8Array(128); // z is 122 in ASCII
@@ -45,3 +48,8 @@ export function encodeInteger(builder: StringWriter, num: number, relative: numb
 
   return num;
 }
+
+export function hasMoreVlq(reader: StringReader, max: number) {
+  if (reader.pos >= max) return false;
+  return reader.peek() !== comma;
+}