5 files changed, 66 insertions, 0 deletions
diff --git a/std/encoding/_yaml/schema/core.ts b/std/encoding/_yaml/schema/core.ts
new file mode 100644
index 000000000..4fadc9bfe
--- /dev/null
+++ b/std/encoding/_yaml/schema/core.ts
@@ -0,0 +1,13 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2011-2015 by Vitaly Puzrin. All rights reserved. MIT license.
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import { Schema } from "../schema.ts";
+import { json } from "./json.ts";
+
+// Standard YAML's Core schema.
+// http://www.yaml.org/spec/1.2/spec.html#id2804923
+export const core = new Schema({
+  include: [json],
+});
diff --git a/std/encoding/_yaml/schema/default.ts b/std/encoding/_yaml/schema/default.ts
new file mode 100644
index 000000000..4c5ceeba7
--- /dev/null
+++ b/std/encoding/_yaml/schema/default.ts
@@ -0,0 +1,16 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2011-2015 by Vitaly Puzrin. All rights reserved. MIT license.
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import { Schema } from "../schema.ts";
+import { binary, merge, omap, pairs, set, timestamp } from "../type/mod.ts";
+import { core } from "./core.ts";
+
+// JS-YAML's default schema for `safeLoad` function.
+// It is not described in the YAML specification.
+export const def = new Schema({
+  explicit: [binary, omap, pairs, set],
+  implicit: [timestamp, merge],
+  include: [core],
+});
diff --git a/std/encoding/_yaml/schema/failsafe.ts b/std/encoding/_yaml/schema/failsafe.ts
new file mode 100644
index 000000000..74e1897be
--- /dev/null
+++ b/std/encoding/_yaml/schema/failsafe.ts
@@ -0,0 +1,13 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2011-2015 by Vitaly Puzrin. All rights reserved. MIT license.
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import { Schema } from "../schema.ts";
+import { map, seq, str } from "../type/mod.ts";
+
+// Standard YAML's Failsafe schema.
+// http://www.yaml.org/spec/1.2/spec.html#id2802346
+export const failsafe = new Schema({
+  explicit: [str, seq, map],
+});
diff --git a/std/encoding/_yaml/schema/json.ts b/std/encoding/_yaml/schema/json.ts
new file mode 100644
index 000000000..c30166fdf
--- /dev/null
+++ b/std/encoding/_yaml/schema/json.ts
@@ -0,0 +1,15 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2011-2015 by Vitaly Puzrin. All rights reserved. MIT license.
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import { Schema } from "../schema.ts";
+import { bool, float, int, nil } from "../type/mod.ts";
+import { failsafe } from "./failsafe.ts";
+
+// Standard YAML's JSON schema.
+// http://www.yaml.org/spec/1.2/spec.html#id2803231
+export const json = new Schema({
+  implicit: [nil, bool, int, float],
+  include: [failsafe],
+});
diff --git a/std/encoding/_yaml/schema/mod.ts b/std/encoding/_yaml/schema/mod.ts
new file mode 100644
index 000000000..7cbe0c283
--- /dev/null
+++ b/std/encoding/_yaml/schema/mod.ts
@@ -0,0 +1,9 @@
+// Ported from js-yaml v3.13.1:
+// https://github.com/nodeca/js-yaml/commit/665aadda42349dcae869f12040d9b10ef18d12da
+// Copyright 2011-2015 by Vitaly Puzrin. All rights reserved. MIT license.
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+export { core as CORE_SCHEMA } from "./core.ts";
+export { def as DEFAULT_SCHEMA } from "./default.ts";
+export { failsafe as FAILSAFE_SCHEMA } from "./failsafe.ts";
+export { json as JSON_SCHEMA } from "./json.ts";