Refactor patch parse

.devcontainer/devcontainer.json

@@ -0,0 +1,25 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/typescript-node
+{
+	"name": "Node.js & TypeScript",
+	// Or use a Dockerfile or Docker Compose file. More info: https://containers.dev/guide/dockerfile
+	"image": "mcr.microsoft.com/devcontainers/typescript-node:5-24-trixie",
+	"features": {
+		"ghcr.io/shyim/devcontainers-features/bun:0": { "version": "latest" }
+	}
+
+	// Features to add to the dev container. More info: https://containers.dev/features.
+	// "features": {},
+
+	// Use 'forwardPorts' to make a list of ports inside the container available locally.
+	// "forwardPorts": [],
+
+	// Use 'postCreateCommand' to run commands after the container is created.
+	// "postCreateCommand": "yarn install",
+
+	// Configure tool-specific properties.
+	// "customizations": {},
+
+	// Uncomment to connect as root instead. More info: https://aka.ms/dev-containers-non-root.
+	// "remoteUser": "root"
+}

packages/core/src/patch.ts

@@ -22,6 +22,54 @@ export interface FileUpdate {
   readonly bom: boolean
 }
 
+const ADD_PREFIX = "*** Add File:"
+const DELETE_PREFIX = "*** Delete File:"
+const UPDATE_PREFIX = "*** Update File:"
+const MOVE_PREFIX = "*** Move to:"
+
+interface ParsedHunk {
+  readonly hunk: Hunk
+  readonly next: number
+}
+
+function directivePath(line: string, prefix: string, error: string): string {
+  const path = line.slice(prefix.length).trim()
+  if (!path) throw new Error(error)
+  return path
+}
+
+function parseAddHunk(lines: ReadonlyArray<string>, index: number): ParsedHunk {
+  const path = directivePath(lines[index]!, ADD_PREFIX, "Invalid add file path")
+  const parsed = parseAdd(lines, index + 1)
+  return { hunk: { type: "add", path, contents: parsed.content }, next: parsed.next }
+}
+
+function parseDeleteHunk(lines: ReadonlyArray<string>, index: number): ParsedHunk {
+  const path = directivePath(lines[index]!, DELETE_PREFIX, "Invalid delete file path")
+  return { hunk: { type: "delete", path }, next: index + 1 }
+}
+
+function parseUpdateHunk(lines: ReadonlyArray<string>, index: number): ParsedHunk {
+  const path = directivePath(lines[index]!, UPDATE_PREFIX, "Invalid update file path")
+  let next = index + 1
+  let movePath: string | undefined
+  if (lines[next]?.startsWith(MOVE_PREFIX)) {
+    movePath = directivePath(lines[next]!, MOVE_PREFIX, "Invalid move file path")
+    next++
+  }
+  const parsed = parseUpdate(lines, next)
+  if (parsed.chunks.length === 0) throw new Error(`Invalid update hunk for ${path}: expected at least one @@ chunk`)
+  return { hunk: { type: "update", path, movePath, chunks: parsed.chunks }, next: parsed.next }
+}
+
+function parseHunk(lines: ReadonlyArray<string>, index: number): ParsedHunk {
+  const line = lines[index]!
+  if (line.startsWith(ADD_PREFIX)) return parseAddHunk(lines, index)
+  if (line.startsWith(DELETE_PREFIX)) return parseDeleteHunk(lines, index)
+  if (line.startsWith(UPDATE_PREFIX)) return parseUpdateHunk(lines, index)
+  throw new Error(`Invalid patch line: ${line}`)
+}
+
 export function parse(patchText: string): ReadonlyArray<Hunk> {
   const lines = stripHeredoc(patchText.trim()).split("\n")
   const begin = lines.findIndex((line) => line.trim() === "*** Begin Patch")
@@ -31,39 +79,9 @@ export function parse(patchText: string): ReadonlyArray<Hunk> {
   const hunks: Hunk[] = []
   let index = begin + 1
   while (index < end) {
-    const line = lines[index]!
-    if (line.startsWith("*** Add File:")) {
-      const path = line.slice("*** Add File:".length).trim()
-      if (!path) throw new Error("Invalid add file path")
-      const parsed = parseAdd(lines, index + 1)
-      hunks.push({ type: "add", path, contents: parsed.content })
-      index = parsed.next
-      continue
-    }
-    if (line.startsWith("*** Delete File:")) {
-      const path = line.slice("*** Delete File:".length).trim()
-      if (!path) throw new Error("Invalid delete file path")
-      hunks.push({ type: "delete", path })
-      index++
-      continue
-    }
-    if (line.startsWith("*** Update File:")) {
-      const path = line.slice("*** Update File:".length).trim()
-      if (!path) throw new Error("Invalid update file path")
-      let next = index + 1
-      let movePath: string | undefined
-      if (lines[next]?.startsWith("*** Move to:")) {
-        movePath = lines[next]!.slice("*** Move to:".length).trim()
-        if (!movePath) throw new Error("Invalid move file path")
-        next++
-      }
-      const parsed = parseUpdate(lines, next)
-      if (parsed.chunks.length === 0) throw new Error(`Invalid update hunk for ${path}: expected at least one @@ chunk`)
-      hunks.push({ type: "update", path, movePath, chunks: parsed.chunks })
-      index = parsed.next
-      continue
-    }
-    throw new Error(`Invalid patch line: ${line}`)
+    const parsed = parseHunk(lines, index)
+    hunks.push(parsed.hunk)
+    index = parsed.next
   }
   return hunks
 }