Range mappings: encoding/decoding support

packages/gen-mapping/package.json

@@ -47,6 +47,7 @@
     "test:format": "prettier --check '{src,test}/**/*.ts'",
     "test:only": "mocha",
     "test:types": "eslint '{src,test}/**/*.ts'",
+    "test:watch": "mocha --watch --watch-files 'src/**/*.ts,test/**/*.ts'",
     "lint": "run-s -n lint:types lint:format",
     "lint:format": "npm run test:format -- --write",
     "lint:types": "npm run test:types -- --fix",

packages/remapping/package.json

@@ -48,6 +48,7 @@
     "test:format": "prettier --check '{src,test}/**/*.ts'",
     "test:only": "mocha",
     "test:types": "eslint '{src,test}/**/*.ts'",
+    "test:watch": "mocha --watch --watch-files 'src/**/*.ts,test/**/*.ts'",
     "lint": "run-s -n lint:types lint:format",
     "lint:format": "npm run test:format -- --write",
     "lint:types": "npm run test:types -- --fix",

packages/source-map/package.json

@@ -48,6 +48,7 @@
     "test:format": "prettier --check '{src,test}/**/*.ts'",
     "test:only": "mocha",
     "test:types": "eslint '{src,test}/**/*.ts'",
+    "test:watch": "mocha --watch --watch-files 'src/**/*.ts,test/**/*.ts'",
     "lint": "run-s -n lint:types lint:format",
     "lint:format": "npm run test:format -- --write",
     "lint:types": "npm run test:types -- --fix",

packages/sourcemap-codec/package.json

@@ -47,6 +47,7 @@
     "test:format": "prettier --check '{src,test}/**/*.ts'",
     "test:only": "mocha",
     "test:types": "eslint '{src,test}/**/*.ts'",
+    "test:watch": "mocha --watch --watch-files 'src/**/*.ts,test/**/*.ts'",
     "lint": "run-s -n lint:types lint:format",
     "lint:format": "npm run test:format -- --write",
     "lint:types": "npm run test:types -- --fix",
@@ -60,4 +61,4 @@
   },
   "author": "Justin Ridgewell <justin@ridgewell.name>",
   "license": "MIT"
-}
+}

packages/sourcemap-codec/src/range-mappings.ts

@@ -0,0 +1,47 @@
+import { StringReader, StringWriter } from './strings';
+import { decodeInteger, encodeInteger, semicolon } from './vlq';
+
+export type MappingIndex = number;
+export type RangeMappings = MappingIndex[][];
+
+export function decodeRangeMappings(input: string): RangeMappings {
+  const { length } = input;
+  const reader = new StringReader(input);
+  const rangeMappings: RangeMappings = [];
+
+  do {
+    const semi = reader.indexOf(';');
+    const indices: MappingIndex[] = [];
+    let index = -1;
+
+    while (reader.pos < semi) {
+      index += decodeInteger(reader);
+      indices.push(index);
+    }
+
+    rangeMappings.push(indices);
+    reader.pos = semi + 1;
+  } while (reader.pos <= length);
+
+  return rangeMappings;
+}
+
+export function encodeRangeMappings(decoded: RangeMappings): string {
+  if (decoded.length === 0) return '';
+
+  const writer = new StringWriter();
+
+  for (let i = 0; i < decoded.length; i++) {
+    const indices = decoded[i];
+    if (i > 0) writer.write(semicolon);
+
+    let index = -1;
+    for (let j = 0; j < indices.length; j++) {
+      const offset = indices[j];
+      encodeInteger(writer, offset - index);
+      index = offset;
+    }
+  }
+
+  return writer.flush();
+}

packages/sourcemap-codec/src/scopes.ts

@@ -1,5 +1,13 @@
 import { StringReader, StringWriter } from './strings';
-import { comma, decodeInteger, encodeInteger, hasMoreVlq, semicolon } from './vlq';
+import {
+  comma,
+  decodeInteger,
+  decodeSign,
+  encodeInteger,
+  encodeSign,
+  hasMoreVlq,
+  semicolon,
+} from './vlq';
 
 const EMPTY: any[] = [];
 
@@ -40,8 +48,8 @@ export function decodeOriginalScopes(input: string): OriginalScope[] {
   let line = 0;
 
   for (; reader.pos < length; reader.pos++) {
-    line = decodeInteger(reader, line);
-    const column = decodeInteger(reader, 0);
+    line += decodeSign(decodeInteger(reader));
+    const column = decodeSign(decodeInteger(reader));
 
     if (!hasMoreVlq(reader, length)) {
       const last = stack.pop()!;
@@ -50,19 +58,21 @@ export function decodeOriginalScopes(input: string): OriginalScope[] {
       continue;
     }
 
-    const kind = decodeInteger(reader, 0);
-    const fields = decodeInteger(reader, 0);
+    const kind = decodeSign(decodeInteger(reader));
+    const fields = decodeSign(decodeInteger(reader));
     const hasName = fields & 0b0001;
 
     const scope: OriginalScope = (
-      hasName ? [line, column, 0, 0, kind, decodeInteger(reader, 0)] : [line, column, 0, 0, kind]
+      hasName
+        ? [line, column, 0, 0, kind, decodeSign(decodeInteger(reader))]
+        : [line, column, 0, 0, kind]
     ) as OriginalScope;
 
     let vars: Var[] = EMPTY;
     if (hasMoreVlq(reader, length)) {
       vars = [];
       do {
-        const varsIndex = decodeInteger(reader, 0);
+        const varsIndex = decodeSign(decodeInteger(reader));
         vars.push(varsIndex);
       } while (hasMoreVlq(reader, length));
     }
@@ -98,16 +108,17 @@ function _encodeOriginalScopes(
 
   if (index > 0) writer.write(comma);
 
-  state[0] = encodeInteger(writer, startLine, state[0]);
-  encodeInteger(writer, startColumn, 0);
-  encodeInteger(writer, kind, 0);
+  encodeInteger(writer, encodeSign(startLine - state[0]));
+  state[0] = startLine;
+  encodeInteger(writer, encodeSign(startColumn));
+  encodeInteger(writer, encodeSign(kind));
 
   const fields = scope.length === 6 ? 0b0001 : 0;
-  encodeInteger(writer, fields, 0);
-  if (scope.length === 6) encodeInteger(writer, scope[5], 0);
+  encodeInteger(writer, encodeSign(fields));
+  if (scope.length === 6) encodeInteger(writer, encodeSign(scope[5]));
 
   for (const v of vars) {
-    encodeInteger(writer, v, 0);
+    encodeInteger(writer, encodeSign(v));
   }
 
   for (index++; index < scopes.length; ) {
@@ -120,8 +131,9 @@ function _encodeOriginalScopes(
   }
 
   writer.write(comma);
-  state[0] = encodeInteger(writer, endLine, state[0]);
-  encodeInteger(writer, endColumn, 0);
+  encodeInteger(writer, encodeSign(endLine - state[0]));
+  state[0] = endLine;
+  encodeInteger(writer, encodeSign(endColumn));
 
   return index;
 }
@@ -146,7 +158,7 @@ export function decodeGeneratedRanges(input: string): GeneratedRange[] {
     let genColumn = 0;
 
     for (; reader.pos < semi; reader.pos++) {
-      genColumn = decodeInteger(reader, genColumn);
+      genColumn += decodeSign(decodeInteger(reader));
 
       if (!hasMoreVlq(reader, semi)) {
         const last = stack.pop()!;
@@ -155,7 +167,7 @@ export function decodeGeneratedRanges(input: string): GeneratedRange[] {
         continue;
       }
 
-      const fields = decodeInteger(reader, 0);
+      const fields = decodeSign(decodeInteger(reader));
       const hasDefinition = fields & 0b0001;
       const hasCallsite = fields & 0b0010;
       const hasScope = fields & 0b0100;
@@ -164,11 +176,10 @@ export function decodeGeneratedRanges(input: string): GeneratedRange[] {
       let bindings: Binding[] = EMPTY;
       let range: GeneratedRange;
       if (hasDefinition) {
-        const defSourcesIndex = decodeInteger(reader, definitionSourcesIndex);
-        definitionScopeIndex = decodeInteger(
-          reader,
-          definitionSourcesIndex === defSourcesIndex ? definitionScopeIndex : 0,
-        );
+        const defSourcesIndex = definitionSourcesIndex + decodeSign(decodeInteger(reader));
+        definitionScopeIndex =
+          decodeSign(decodeInteger(reader)) +
+          (definitionSourcesIndex === defSourcesIndex ? definitionScopeIndex : 0);
 
         definitionSourcesIndex = defSourcesIndex;
         range = [genLine, genColumn, 0, 0, defSourcesIndex, definitionScopeIndex] as GeneratedRange;
@@ -181,13 +192,12 @@ export function decodeGeneratedRanges(input: string): GeneratedRange[] {
       if (hasCallsite) {
         const prevCsi = callsiteSourcesIndex;
         const prevLine = callsiteLine;
-        callsiteSourcesIndex = decodeInteger(reader, callsiteSourcesIndex);
+        callsiteSourcesIndex += decodeSign(decodeInteger(reader));
         const sameSource = prevCsi === callsiteSourcesIndex;
-        callsiteLine = decodeInteger(reader, sameSource ? callsiteLine : 0);
-        callsiteColumn = decodeInteger(
-          reader,
-          sameSource && prevLine === callsiteLine ? callsiteColumn : 0,
-        );
+        callsiteLine = (sameSource ? callsiteLine : 0) + decodeSign(decodeInteger(reader));
+        callsiteColumn =
+          (sameSource && prevLine === callsiteLine ? callsiteColumn : 0) +
+          decodeSign(decodeInteger(reader));
 
         callsite = [callsiteSourcesIndex, callsiteLine, callsiteColumn];
       }
@@ -198,15 +208,16 @@ export function decodeGeneratedRanges(input: string): GeneratedRange[] {
         do {
           bindingLine = genLine;
           bindingColumn = genColumn;
-          const expressionsCount = decodeInteger(reader, 0);
+          const expressionsCount = decodeSign(decodeInteger(reader));
           let expressionRanges: BindingExpressionRange[];
           if (expressionsCount < -1) {
-            expressionRanges = [[decodeInteger(reader, 0)]];
+            expressionRanges = [[decodeSign(decodeInteger(reader))]];
             for (let i = -1; i > expressionsCount; i--) {
               const prevBl = bindingLine;
-              bindingLine = decodeInteger(reader, bindingLine);
-              bindingColumn = decodeInteger(reader, bindingLine === prevBl ? bindingColumn : 0);
-              const expression = decodeInteger(reader, 0);
+              bindingLine += decodeSign(decodeInteger(reader));
+              bindingColumn =
+                (bindingLine === prevBl ? bindingColumn : 0) + decodeSign(decodeInteger(reader));
+              const expression = decodeSign(decodeInteger(reader));
               expressionRanges.push([expression, bindingLine, bindingColumn]);
             }
           } else {
@@ -273,19 +284,22 @@ function _encodeGeneratedRanges(
     writer.write(comma);
   }
 
-  state[1] = encodeInteger(writer, range[1], state[1]);
+  encodeInteger(writer, encodeSign(range[1] - state[1]));
+  state[1] = range[1];
 
   const fields =
     (range.length === 6 ? 0b0001 : 0) | (callsite ? 0b0010 : 0) | (isScope ? 0b0100 : 0);
-  encodeInteger(writer, fields, 0);
+  encodeInteger(writer, encodeSign(fields));
 
   if (range.length === 6) {
     const { 4: sourcesIndex, 5: scopesIndex } = range;
     if (sourcesIndex !== state[2]) {
       state[3] = 0;
     }
-    state[2] = encodeInteger(writer, sourcesIndex, state[2]);
-    state[3] = encodeInteger(writer, scopesIndex, state[3]);
+    encodeInteger(writer, encodeSign(sourcesIndex - state[2]));
+    state[2] = sourcesIndex;
+    encodeInteger(writer, encodeSign(scopesIndex - state[3]));
+    state[3] = scopesIndex;
   }
 
   if (callsite) {
@@ -296,23 +310,28 @@ function _encodeGeneratedRanges(
     } else if (callLine !== state[5]) {
       state[6] = 0;
     }
-    state[4] = encodeInteger(writer, sourcesIndex, state[4]);
-    state[5] = encodeInteger(writer, callLine, state[5]);
-    state[6] = encodeInteger(writer, callColumn, state[6]);
+    encodeInteger(writer, encodeSign(sourcesIndex - state[4]));
+    state[4] = sourcesIndex;
+    encodeInteger(writer, encodeSign(callLine - state[5]));
+    state[5] = callLine;
+    encodeInteger(writer, encodeSign(callColumn - state[6]));
+    state[6] = callColumn;
   }
 
   if (bindings) {
     for (const binding of bindings) {
-      if (binding.length > 1) encodeInteger(writer, -binding.length, 0);
+      if (binding.length > 1) encodeInteger(writer, encodeSign(-binding.length));
       const expression = binding[0][0];
-      encodeInteger(writer, expression, 0);
+      encodeInteger(writer, encodeSign(expression));
       let bindingStartLine = startLine;
       let bindingStartColumn = startColumn;
       for (let i = 1; i < binding.length; i++) {
         const expRange = binding[i];
-        bindingStartLine = encodeInteger(writer, expRange[1]!, bindingStartLine);
-        bindingStartColumn = encodeInteger(writer, expRange[2]!, bindingStartColumn);
-        encodeInteger(writer, expRange[0]!, 0);
+        encodeInteger(writer, encodeSign(expRange[1]! - bindingStartLine));
+        bindingStartLine = expRange[1]!;
+        encodeInteger(writer, encodeSign(expRange[2]! - bindingStartColumn));
+        bindingStartColumn = expRange[2]!;
+        encodeInteger(writer, encodeSign(expRange[0]!));
       }
     }
   }
@@ -333,7 +352,8 @@ function _encodeGeneratedRanges(
   } else {
     writer.write(comma);
   }
-  state[1] = encodeInteger(writer, endColumn, state[1]);
+  encodeInteger(writer, encodeSign(endColumn - state[1]));
+  state[1] = endColumn;
 
   return index;
 }

packages/sourcemap-codec/src/sourcemap-codec.ts

@@ -1,4 +1,12 @@
-import { comma, decodeInteger, encodeInteger, hasMoreVlq, semicolon } from './vlq';
+import {
+  comma,
+  decodeInteger,
+  decodeSign,
+  encodeInteger,
+  encodeSign,
+  hasMoreVlq,
+  semicolon,
+} from './vlq';
 import { StringWriter, StringReader } from './strings';
 
 export {
@@ -9,6 +17,9 @@ export {
 } from './scopes';
 export type { OriginalScope, GeneratedRange, CallSite, BindingExpressionRange } from './scopes';
 
+export { decodeRangeMappings, encodeRangeMappings } from './range-mappings';
+export type { MappingIndex, RangeMappings } from './range-mappings';
+
 export type SourceMapSegment =
   | [number]
   | [number, number, number, number]
@@ -36,17 +47,17 @@ export function decode(mappings: string): SourceMapMappings {
     while (reader.pos < semi) {
       let seg: SourceMapSegment;
 
-      genColumn = decodeInteger(reader, genColumn);
+      genColumn += decodeSign(decodeInteger(reader));
       if (genColumn < lastCol) sorted = false;
       lastCol = genColumn;
 
       if (hasMoreVlq(reader, semi)) {
-        sourcesIndex = decodeInteger(reader, sourcesIndex);
-        sourceLine = decodeInteger(reader, sourceLine);
-        sourceColumn = decodeInteger(reader, sourceColumn);
+        sourcesIndex += decodeSign(decodeInteger(reader));
+        sourceLine += decodeSign(decodeInteger(reader));
+        sourceColumn += decodeSign(decodeInteger(reader));
 
         if (hasMoreVlq(reader, semi)) {
-          namesIndex = decodeInteger(reader, namesIndex);
+          namesIndex += decodeSign(decodeInteger(reader));
           seg = [genColumn, sourcesIndex, sourceLine, sourceColumn, namesIndex];
         } else {
           seg = [genColumn, sourcesIndex, sourceLine, sourceColumn];
@@ -95,15 +106,20 @@ export function encode(decoded: Readonly<SourceMapMappings>): string {
       const segment = line[j];
       if (j > 0) writer.write(comma);
 
-      genColumn = encodeInteger(writer, segment[0], genColumn);
+      encodeInteger(writer, encodeSign(segment[0] - genColumn));
+      genColumn = segment[0];
 
       if (segment.length === 1) continue;
-      sourcesIndex = encodeInteger(writer, segment[1], sourcesIndex);
-      sourceLine = encodeInteger(writer, segment[2], sourceLine);
-      sourceColumn = encodeInteger(writer, segment[3], sourceColumn);
+      encodeInteger(writer, encodeSign(segment[1] - sourcesIndex));
+      encodeInteger(writer, encodeSign(segment[2] - sourceLine));
+      encodeInteger(writer, encodeSign(segment[3] - sourceColumn));
+      sourcesIndex = segment[1];
+      sourceLine = segment[2];
+      sourceColumn = segment[3];
 
       if (segment.length === 4) continue;
-      namesIndex = encodeInteger(writer, segment[4], namesIndex);
+      encodeInteger(writer, encodeSign(segment[4] - namesIndex));
+      namesIndex = segment[4];
     }
   }