encoding/jsonschema: decode required properties as required fields

Decode a jsonschema required property as a CUE required field
instead of a regular field.

Fixes #3318

Change-Id: Idc856b888e682cd0ea9124277371681d0a83898c
Signed-off-by: haoqixu <hq.xu0o0@gmail.com>
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1198831
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>

cmd/cue/cmd/testdata/script/def_openapi.txtar

@@ -218,12 +218,12 @@ info: {
 	version: *"v1alpha1" | string
 }
 #Bar: {
-	foo: #Foo
+	foo!: #Foo
 	...
 }
 #Foo: {
-	a: int
-	b: uint & <10
+	a!: int
+	b!: uint & <10
 	...
 }
 -- expect-cue2 --
@@ -232,12 +232,12 @@ info: {
 	version: *"v1" | string
 }
 #Bar: {
-	foo: #Foo
+	foo!: #Foo
 	...
 }
 #Foo: {
-	a: int
-	b: uint & <10
+	a!: int
+	b!: uint & <10
 	...
 }
 -- expect-cue3 --
@@ -251,17 +251,17 @@ info: {
 	version: (*"v1alpha1" | string) & (*"v1alpha1" | string)
 }
 #Bar: {
-	foo: #Foo
+	foo!: #Foo
 	...
 }
 #Foo: {
-	a: int
-	b: uint & <10
+	a!: int
+	b!: uint & <10
 	...
 }
 #Baz: {
-	a: int
-	b: uint & <10
+	a!: int
+	b!: uint & <10
 	...
 }
 -- expect-out.cue --

cmd/cue/cmd/testdata/script/embed.txtar

@@ -149,14 +149,14 @@ f: {
         version: "v1alpha1"
     }
     #Bar: {
-        foo: {
-            a: int
-            b: uint & <10
+        foo!: {
+            a!: int
+            b!: uint & <10
         }
     }
     #Foo: {
-        a: int
-        b: uint & <10
+        a!: int
+        b!: uint & <10
     }
 }
 g: {

cmd/cue/cmd/testdata/script/import_auto.txtar

@@ -22,12 +22,12 @@ info: {
 }
 
 #Foo: {
-	a: int
-	b: int & <10 & >=0
+	a!: int
+	b!: int & <10 & >=0
 	...
 }
 #Bar: {
-	foo: #Foo
+	foo!: #Foo
 	...
 }
 -- openapi.yaml --

encoding/jsonschema/constraints.go

@@ -516,8 +516,9 @@ var constraints = []*constraint{
 			f := fields[str]
 			if f == nil && ok {
 				f := &ast.Field{
-					Label: ast.NewString(str),
-					Value: ast.NewIdent("_"),
+					Label:      ast.NewString(str),
+					Value:      ast.NewIdent("_"),
+					Constraint: token.NOT,
 				}
 				fields[str] = f
 				obj.Elts = append(obj.Elts, f)
@@ -526,6 +527,7 @@ var constraints = []*constraint{
 			if f.Optional == token.NoPos {
 				s.errf(n, "duplicate required field %q", str)
 			}
+			f.Constraint = token.NOT
 			f.Optional = token.NoPos
 		}
 	}),

encoding/jsonschema/testdata/basic.txtar

@@ -47,7 +47,7 @@ import "strings"
 
 // A person is a human being.
 person?: {
-	name: string
+	name!: string
 
 	// where does this person live?
 	address?: strings.MinRunes(4) & strings.MaxRunes(20)

encoding/jsonschema/testdata/def.txtar

@@ -46,9 +46,9 @@ billing_address?:  #address
 shipping_address?: #address
 
 #address: {
-	street_address: string
-	city:           string
-	state:          string
+	street_address!: string
+	city!:           string
+	state!:          string
 	...
 }
 

encoding/jsonschema/testdata/required.txtar

@@ -0,0 +1,30 @@
+-- schema.json --
+{
+  "$schema": "http://json-schema.org/draft-04/schema#",
+  "additionalProperties": false,
+  "id": "https://example.test/example",
+  "required": ["x", "z"],
+  "title": "example jsonschema",
+  "type": "object",
+  "properties": {
+    "x": {
+      "description": "A required field",
+      "type": "number"
+    },
+    "y": {
+      "description": "An optional field",
+      "type": "number"
+    }
+  }
+}
+
+-- out/decode/cue --
+// example jsonschema
+@jsonschema(schema="http://json-schema.org/draft-04/schema#")
+
+// A required field
+x!: number
+
+// An optional field
+y?: number
+z!: _