add source map entries for all lines in formatted range

packages/chrome-devtools-formatter/src/index.ts

@@ -50,6 +50,19 @@ export async function formatWithMap(
   return { mapping, content: formatted.formattedContent };
 }
 
+export interface Mapping {
+  generated: {
+    line: number;
+    column: number;
+    offset: number;
+  };
+  original: {
+    line: number;
+    column: number;
+    offset: number;
+  };
+}
+
 export class Mapper {
   constructor(
     public original: string,
@@ -83,7 +96,7 @@ export class Mapper {
     );
   }
 
-  *iterateMappings() {
+  *iterateMappings(): Generator<Mapping> {
     for (let i = 0; i < this.mapping.formatted.length; i++) {
       const generated = this.positionToLocationFormatted(
         this.mapping.formatted[i]

packages/chrome-devtools-formatter/src/source-maps.ts

@@ -1,23 +1,60 @@
-import { Mapper } from ".";
+import { Mapper, Mapping } from ".";
 
 // TODO when a range spans a newline, only the part on the first line is mapped
 export async function toMappings(mapper: Mapper, sourceIndex = -1) {
   let data = new Int32Array(1024);
   let len = 0;
+  let prev: Mapping | undefined;
   for (const m of mapper.iterateMappings()) {
     if (data.length < len + 6) {
       const expanded = new Int32Array(data.length * 2);
       expanded.set(data);
       data = expanded;
     }
 
+    /*
+    AAA
+    AAA
+    AAA
+    BBB
+
+    AAA
+    AAA
+    ABB
+
+    */
+
+    if (prev) {
+      const extraLines =
+        m.generated.line -
+        (prev.generated.line + 1 < m.generated.line
+          ? prev.generated.line + 1
+          : prev.generated.line !== m.generated.line && m.generated.column !== 0
+          ? prev.generated.line
+          : m.generated.line);
+
+      // TODO is this only handling when the original was already formatted?
+      // no? at least not internally - maybe only at the end
+      for (let i = 0; i < extraLines; i++) {
+        data[len + 0] = i + prev.generated.line + 1;
+        data[len + 1] = 0;
+        data[len + 2] = sourceIndex;
+        data[len + 3] = i + prev.original.line + 1;
+        data[len + 4] = 0;
+        data[len + 5] = -1;
+        len += 6;
+      }
+    }
+
     data[len + 0] = m.generated.line;
     data[len + 1] = m.generated.column;
     data[len + 2] = sourceIndex;
     data[len + 3] = m.original.line;
     data[len + 4] = m.original.column;
     data[len + 5] = -1;
     len += 6;
+
+    prev = m;
   }
 
   return data.subarray(0, len);