1 files changed, 105 insertions, 0 deletions
diff --git a/cli/js/ops/io.ts b/cli/js/ops/io.ts
new file mode 100644
index 000000000..9f53707b7
--- /dev/null
+++ b/cli/js/ops/io.ts
@@ -0,0 +1,105 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import { sendAsyncMinimal, sendSyncMinimal } from "./dispatch_minimal.ts";
+import { EOF } from "../io.ts";
+// TODO(bartlomieju): remove this import and maybe lazy-initialize
+// OPS_CACHE that belongs only to this module
+import { OPS_CACHE } from "../runtime.ts";
+
+// This is done because read/write are extremely performance sensitive.
+let OP_READ = -1;
+let OP_WRITE = -1;
+
+/** Synchronously read from a file ID into an array buffer.
+ *
+ * Returns `number | EOF` for the operation.
+ *
+ *      const file = Deno.openSync("/foo/bar.txt");
+ *      const buf = new Uint8Array(100);
+ *      const nread = Deno.readSync(file.rid, buf);
+ *      const text = new TextDecoder().decode(buf);
+ */
+export function readSync(rid: number, p: Uint8Array): number | EOF {
+  if (p.length == 0) {
+    return 0;
+  }
+  if (OP_READ < 0) {
+    OP_READ = OPS_CACHE["op_read"];
+  }
+  const nread = sendSyncMinimal(OP_READ, rid, p);
+  if (nread < 0) {
+    throw new Error("read error");
+  } else if (nread == 0) {
+    return EOF;
+  } else {
+    return nread;
+  }
+}
+
+/** Read from a resource ID into an array buffer.
+ *
+ * Resolves to the `number | EOF` for the operation.
+ *
+ *       const file = await Deno.open("/foo/bar.txt");
+ *       const buf = new Uint8Array(100);
+ *       const nread = await Deno.read(file.rid, buf);
+ *       const text = new TextDecoder().decode(buf);
+ */
+export async function read(rid: number, p: Uint8Array): Promise<number | EOF> {
+  if (p.length == 0) {
+    return 0;
+  }
+  if (OP_READ < 0) {
+    OP_READ = OPS_CACHE["op_read"];
+  }
+  const nread = await sendAsyncMinimal(OP_READ, rid, p);
+  if (nread < 0) {
+    throw new Error("read error");
+  } else if (nread == 0) {
+    return EOF;
+  } else {
+    return nread;
+  }
+}
+
+/** Synchronously write to the resource ID the contents of the array buffer.
+ *
+ * Resolves to the number of bytes written.
+ *
+ *       const encoder = new TextEncoder();
+ *       const data = encoder.encode("Hello world\n");
+ *       const file = Deno.openSync("/foo/bar.txt", {create: true, write: true});
+ *       Deno.writeSync(file.rid, data);
+ */
+export function writeSync(rid: number, p: Uint8Array): number {
+  if (OP_WRITE < 0) {
+    OP_WRITE = OPS_CACHE["op_write"];
+  }
+  const result = sendSyncMinimal(OP_WRITE, rid, p);
+  if (result < 0) {
+    throw new Error("write error");
+  } else {
+    return result;
+  }
+}
+
+/** Write to the resource ID the contents of the array buffer.
+ *
+ * Resolves to the number of bytes written.
+ *
+ *      const encoder = new TextEncoder();
+ *      const data = encoder.encode("Hello world\n");
+ *      const file = await Deno.open("/foo/bar.txt", {create: true, write: true});
+ *      await Deno.write(file.rid, data);
+ */
+export async function write(rid: number, p: Uint8Array): Promise<number> {
+  if (OP_WRITE < 0) {
+    OP_WRITE = OPS_CACHE["op_write"];
+  }
+  const result = await sendAsyncMinimal(OP_WRITE, rid, p);
+  if (result < 0) {
+    throw new Error("write error");
+  } else {
+    return result;
+  }
+}