refactor(BREAKING): command pipe writes may now return a promise

mod.test.ts

@@ -95,7 +95,7 @@ Deno.test("should not get stderr when set to writer", async () => {
   assertThrows(
     () => output.stderr,
     Error,
-    `Stderr was not piped (was streamed). Call .stderr(\"piped\") or .stderr(\"inheritPiped\") when building the command.`,
+    `Stderr was streamed to another source and is no longer available.`,
   );
 });
 
@@ -374,14 +374,11 @@ Deno.test("should handle boolean list 'and'", async () => {
 
 Deno.test("should support custom command handlers", async () => {
   const builder = new CommandBuilder()
-    .registerCommand("zardoz-speaks", (context) => {
+    .registerCommand("zardoz-speaks", async (context) => {
       if (context.args.length != 1) {
-        context.stderr.writeLine("zardoz-speaks: expected 1 argument");
-        return {
-          code: 1,
-        };
+        return context.error("zardoz-speaks: expected 1 argument");
       }
-      context.stdout.writeLine(`zardoz speaks to ${context.args[0]}`);
+      await context.stdout.writeLine(`zardoz speaks to ${context.args[0]}`);
       return {
         code: 0,
       };
@@ -802,7 +799,7 @@ Deno.test("piping to stdin", async () => {
       .stderr("piped")
       .noThrow();
     assertEquals(result.code, 1);
-    assertEquals(result.stderr, "stdin pipe broken. Error: Exited with code: 1\n");
+    assertEquals(result.stderr, "stdin pipe broken. Exited with code: 1\n");
   }
 });
 
@@ -862,13 +859,9 @@ Deno.test("piping to a writable that throws", async () => {
       throw new Error("failed");
     },
   });
-  await assertRejects(
-    async () => {
-      await $`echo 1`.stdout(writableStream);
-    },
-    Error,
-    "failed",
-  );
+  const result = await $`echo 1`.stdout(writableStream).stderr("piped").noThrow();
+  assertEquals(result.code, 1);
+  assertEquals(result.stderr, "echo: failed\n");
 });
 
 Deno.test("piping stdout/stderr to a file", async () => {
@@ -1030,7 +1023,7 @@ Deno.test("streaming api errors while streaming", async () => {
       .stdout("piped")
       .stderr("piped")
       .spawn();
-    assertEquals(result.stderr, "stdin pipe broken. Error: Exited with code: 1\n");
+    assertEquals(result.stderr, "stdin pipe broken. Exited with code: 1\n");
     assertEquals(result.stdout, "1\n2\n");
   }
 });

src/command.ts

@@ -18,19 +18,22 @@ import { Delay } from "./common.ts";
 import { Buffer, colors, path, readerFromStreamReader } from "./deps.ts";
 import {
   CapturingBufferWriter,
+  CapturingBufferWriterSync,
   InheritStaticTextBypassWriter,
   NullPipeWriter,
   PipedBuffer,
   Reader,
   ShellPipeReaderKind,
   ShellPipeWriter,
   ShellPipeWriterKind,
+  Writer,
   WriterSync,
 } from "./pipes.ts";
 import { parseCommand, spawn } from "./shell.ts";
 import { isShowingProgressBars } from "./console/progress/interval.ts";
 import { PathRef } from "./path.ts";
 import { RequestBuilder } from "./request.ts";
+import { writerFromStreamWriter } from "https://deno.land/std@0.213.0/streams/writer_from_stream_writer.ts";
 
 type BufferStdio = "inherit" | "null" | "streamed" | Buffer;
 
@@ -823,74 +826,57 @@ export function parseAndSpawnCommand(state: CommandBuilderState) {
       }
       const combinedBuffer = new Buffer();
       return [
-        new CapturingBufferWriter(stdoutBuffer, combinedBuffer),
-        new CapturingBufferWriter(stderrBuffer, combinedBuffer),
+        getCapturingBuffer(stdoutBuffer, combinedBuffer),
+        getCapturingBuffer(stderrBuffer, combinedBuffer),
         combinedBuffer,
       ] as const;
     }
     return [stdoutBuffer, stderrBuffer, undefined] as const;
 
-    function getOutputBuffer(innerWriter: WriterSync, { kind, options }: ShellPipeWriterKindWithOptions) {
+    function getCapturingBuffer(buffer: Writer | WriterSync, combinedBuffer: Buffer) {
+      if ("write" in buffer) {
+        return new CapturingBufferWriter(buffer, combinedBuffer);
+      } else {
+        return new CapturingBufferWriterSync(buffer, combinedBuffer);
+      }
+    }
+
+    function getOutputBuffer(inheritWriter: WriterSync, { kind, options }: ShellPipeWriterKindWithOptions) {
       if (typeof kind === "object") {
         if (kind instanceof PathRef) {
           const file = kind.openSync({ write: true, truncate: true, create: true });
           disposables.push(file);
           return file;
         } else if (kind instanceof WritableStream) {
-          // this is sketch
-          const writer = kind.getWriter();
-          const promiseMap = new Map<number, Promise<void>>();
-          let hadError = false;
-          let foundErr: unknown = undefined;
-          let index = 0;
+          const streamWriter = kind.getWriter();
           asyncDisposables.push({
             async [Symbol.asyncDispose]() {
-              await Promise.all(promiseMap.values());
-              if (foundErr) {
-                throw foundErr;
-              }
-              if (!options?.preventClose && !hadError) {
-                await writer.close();
+              streamWriter.releaseLock();
+              if (!options?.preventClose) {
+                try {
+                  await kind.close();
+                } catch {
+                  // ignore, the stream have errored
+                }
               }
             },
           });
-          return {
-            writeSync(buffer: Uint8Array) {
-              if (foundErr) {
-                const errorToThrow = foundErr;
-                foundErr = undefined;
-                throw errorToThrow;
-              }
-              const newIndex = index++;
-              promiseMap.set(
-                newIndex,
-                writer.write(buffer).catch((err) => {
-                  if (err != null) {
-                    foundErr = err;
-                    hadError = true;
-                  }
-                }).finally(() => {
-                  promiseMap.delete(newIndex);
-                }),
-              );
-              return buffer.length;
-            },
-          };
+          return writerFromStreamWriter(streamWriter);
         } else {
           return kind;
         }
       }
       switch (kind) {
         case "inherit":
           if (hasProgressBars) {
-            return new InheritStaticTextBypassWriter(innerWriter);
+            return new InheritStaticTextBypassWriter(inheritWriter);
           } else {
             return "inherit";
           }
         case "piped":
           return new PipedBuffer();
         case "inheritPiped":
-          return new CapturingBufferWriter(innerWriter, new Buffer());
+          return new CapturingBufferWriterSync(inheritWriter, new Buffer());
         case "null":
           return "null";
         default: {
@@ -902,9 +888,17 @@ export function parseAndSpawnCommand(state: CommandBuilderState) {
   }
 
   function finalizeCommandResultBuffer(
-    buffer: PipedBuffer | "inherit" | "null" | CapturingBufferWriter | InheritStaticTextBypassWriter | WriterSync,
+    buffer:
+      | PipedBuffer
+      | "inherit"
+      | "null"
+      | CapturingBufferWriter
+      | CapturingBufferWriterSync
+      | InheritStaticTextBypassWriter
+      | Writer
+      | WriterSync,
   ): BufferStdio {
-    if (buffer instanceof CapturingBufferWriter) {
+    if (buffer instanceof CapturingBufferWriterSync || buffer instanceof CapturingBufferWriter) {
       return buffer.getBuffer();
     } else if (buffer instanceof InheritStaticTextBypassWriter) {
       buffer.flush(); // this is line buffered, so flush anything left
@@ -920,7 +914,15 @@ export function parseAndSpawnCommand(state: CommandBuilderState) {
   }
 
   function finalizeCommandResultBufferForError(
-    buffer: PipedBuffer | "inherit" | "null" | CapturingBufferWriter | InheritStaticTextBypassWriter | WriterSync,
+    buffer:
+      | PipedBuffer
+      | "inherit"
+      | "null"
+      | CapturingBufferWriter
+      | CapturingBufferWriterSync
+      | InheritStaticTextBypassWriter
+      | Writer
+      | WriterSync,
     error: Error,
   ) {
     if (buffer instanceof InheritStaticTextBypassWriter) {
@@ -1013,7 +1015,7 @@ export class CommandResult {
 
   /** Raw stderr bytes. */
   get stderrBytes(): Uint8Array {
-    if (this.#stdout === "streamed") {
+    if (this.#stderr === "streamed") {
       throw new Error(
         `Stderr was streamed to another source and is no longer available.`,
       );

src/command_handler.ts

@@ -1,15 +1,15 @@
 import { ExecuteResult } from "./result.ts";
 import type { KillSignal } from "./command.ts";
-import { Reader, WriterSync } from "./pipes.ts";
+import { Reader } from "./pipes.ts";
 
 /** Used to read from stdin. */
 export type CommandPipeReader = "inherit" | "null" | Reader;
 
 /** Used to write to stdout or stderr. */
-export interface CommandPipeWriter extends WriterSync {
-  writeSync(p: Uint8Array): number;
-  writeText(text: string): void;
-  writeLine(text: string): void;
+export interface CommandPipeWriter {
+  write(p: Uint8Array): Promise<number> | number;
+  writeText(text: string): Promise<void> | void;
+  writeLine(text: string): Promise<void> | void;
 }
 
 /** Context of the currently executing command. */
@@ -21,6 +21,10 @@ export interface CommandContext {
   get stdout(): CommandPipeWriter;
   get stderr(): CommandPipeWriter;
   get signal(): KillSignal;
+  /// Helper function for writing a line to stderr and returning a 1 exit code.
+  error(message: string): Promise<ExecuteResult> | ExecuteResult;
+  /// Helper function for writing a line to stderr and returning the provided exit code.
+  error(code: number, message: string): Promise<ExecuteResult> | ExecuteResult;
 }
 
 /** Handler for executing a command. */

src/commands/cat.ts

@@ -14,8 +14,7 @@ export async function catCommand(
     const code = await executeCat(context);
     return { code };
   } catch (err) {
-    context.stderr.writeLine(`cat: ${err?.message ?? err}`);
-    return { code: 1 };
+    return context.error(`cat: ${err?.message ?? err}`);
   }
 }
 
@@ -29,8 +28,14 @@ async function executeCat(context: CommandContext) {
       if (typeof context.stdin === "object") { // stdin is a Reader
         while (!context.signal.aborted) {
           const size = await context.stdin.read(buf);
-          if (!size || size === 0) break;
-          else context.stdout.writeSync(buf.slice(0, size));
+          if (!size || size === 0) {
+            break;
+          } else {
+            const maybePromise = context.stdout.write(buf.slice(0, size));
+            if (maybePromise instanceof Promise) {
+              await maybePromise;
+            }
+          }
         }
         exitCode = context.signal.abortedExitCode ?? 0;
       } else {
@@ -44,15 +49,24 @@ async function executeCat(context: CommandContext) {
         while (!context.signal.aborted) {
           // NOTE: rust supports cancellation here
           const size = file.readSync(buf);
-          if (!size || size === 0) break;
-          else context.stdout.writeSync(buf.slice(0, size));
+          if (!size || size === 0) {
+            break;
+          } else {
+            const maybePromise = context.stdout.write(buf.slice(0, size));
+            if (maybePromise instanceof Promise) {
+              await maybePromise;
+            }
+          }
         }
         exitCode = context.signal.abortedExitCode ?? 0;
       } catch (err) {
-        context.stderr.writeLine(`cat ${path}: ${err}`);
+        const maybePromise = context.stderr.writeLine(`cat ${path}: ${err?.message ?? err}`);
+        if (maybePromise instanceof Promise) {
+          await maybePromise;
+        }
         exitCode = 1;
       } finally {
-        if (file) file.close();
+        file?.close();
       }
     }
   }
@@ -62,10 +76,15 @@ async function executeCat(context: CommandContext) {
 export function parseCatArgs(args: string[]): CatFlags {
   const paths = [];
   for (const arg of parseArgKinds(args)) {
-    if (arg.kind === "Arg") paths.push(arg.arg);
-    else bailUnsupported(arg); // for now, we don't support any arguments
+    if (arg.kind === "Arg") {
+      paths.push(arg.arg);
+    } else {
+      bailUnsupported(arg); // for now, we don't support any arguments
+    }
   }
 
-  if (paths.length === 0) paths.push("-");
+  if (paths.length === 0) {
+    paths.push("-");
+  }
   return { paths };
 }

src/commands/cd.ts

@@ -13,8 +13,7 @@ export async function cdCommand(context: CommandContext): Promise<ExecuteResult>
       }],
     };
   } catch (err) {
-    context.stderr.writeLine(`cd: ${err?.message ?? err}`);
-    return { code: 1 };
+    return context.error(`cd: ${err?.message ?? err}`);
   }
 }
 

src/commands/cp_mv.ts

@@ -11,8 +11,7 @@ export async function cpCommand(
     await executeCp(context.cwd, context.args);
     return { code: 0 };
   } catch (err) {
-    context.stderr.writeLine(`cp: ${err?.message ?? err}`);
-    return { code: 1 };
+    return context.error(`cp: ${err?.message ?? err}`);
   }
 }
 
@@ -101,8 +100,7 @@ export async function mvCommand(
     await executeMove(context.cwd, context.args);
     return { code: 0 };
   } catch (err) {
-    context.stderr.writeLine(`mv: ${err?.message ?? err}`);
-    return { code: 1 };
+    return context.error(`mv: ${err?.message ?? err}`);
   }
 }
 

src/commands/echo.ts

@@ -1,7 +1,19 @@
 import { CommandContext } from "../command_handler.ts";
 import { ExecuteResult } from "../result.ts";
 
-export function echoCommand(context: CommandContext): ExecuteResult {
-  context.stdout.writeLine(context.args.join(" "));
-  return { code: 0 };
+export function echoCommand(context: CommandContext): ExecuteResult | Promise<ExecuteResult> {
+  try {
+    const maybePromise = context.stdout.writeLine(context.args.join(" "));
+    if (maybePromise instanceof Promise) {
+      return maybePromise.then(() => ({ code: 0 })).catch((err) => handleFailure(context, err));
+    } else {
+      return { code: 0 };
+    }
+  } catch (err) {
+    return handleFailure(context, err);
+  }
+}
+
+function handleFailure(context: CommandContext, err: any) {
+  return context.error(`echo: ${err?.message ?? err}`);
 }