encoding/jsonschema: implement if/then/else keywords

Use the newly added `matchIf` builtin to implement the
JSON Schema conditional operator.

Signed-off-by: Roger Peppe <[email protected]>
Change-Id: I0a64a67683d573f4bc348fb6704f7b18ac3339a7
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1200945
TryBot-Result: CUEcueckoo <[email protected]>
Reviewed-by: Daniel Martí <[email protected]>
Unity-Result: CUE porcuepine <[email protected]>

Author: rogpeppe

cue.mod/pkg/github.com/SchemaStore/schemastore/src/schemas/json/github-workflow.cue

@@ -394,7 +394,37 @@ import (
 			// converted to lowercase during runtime. We recommended using
 			// lowercase input ids.
 			inputs?: {
-				{[=~"^[_a-zA-Z][a-zA-Z0-9_-]*$" & !~"^()$"]: {
+				{[=~"^[_a-zA-Z][a-zA-Z0-9_-]*$" & !~"^()$"]: matchN(5, [matchIf(null | bool | number | string | [...] | {
+					type!: "string", ...
+				}, null | bool | number | string | [...] | {
+					default?: string, ...
+				}, _) & {
+					...
+				}, matchIf(null | bool | number | string | [...] | {
+					type!: "boolean", ...
+				}, null | bool | number | string | [...] | {
+					default?: bool, ...
+				}, _) & {
+					...
+				}, matchIf(null | bool | number | string | [...] | {
+					type!: "number", ...
+				}, null | bool | number | string | [...] | {
+					default?: number, ...
+				}, _) & {
+					...
+				}, matchIf(null | bool | number | string | [...] | {
+					type!: "environment", ...
+				}, null | bool | number | string | [...] | {
+					default?: string, ...
+				}, _) & {
+					...
+				}, matchIf(null | bool | number | string | [...] | {
+					type!: "choice", ...
+				}, null | bool | number | string | [...] | {
+					options!: _, ...
+				}, _) & {
+					...
+				}]) & {
 					// A string description of the input parameter.
 					description!: string
 

encoding/jsonschema/constraints.go

@@ -90,7 +90,7 @@ var constraints = []*constraint{
 	p2("deprecated", constraintDeprecated, vfrom(VersionDraft2019_09)|openAPI),
 	p2("description", constraintDescription, allVersions|openAPI),
 	p1("discriminator", constraintTODO, openAPI),
-	p1("else", constraintTODO, vfrom(VersionDraft7)),
+	p1("else", constraintElse, vfrom(VersionDraft7)),
 	p2("enum", constraintEnum, allVersions|openAPI),
 	p1("example", constraintTODO, openAPI),
 	p2("examples", constraintExamples, vfrom(VersionDraft6)),
@@ -99,7 +99,7 @@ var constraints = []*constraint{
 	p1("externalDocs", constraintTODO, openAPI),
 	p1("format", constraintTODO, allVersions|openAPI),
 	p1("id", constraintID, vto(VersionDraft4)),
-	p1("if", constraintTODO, vfrom(VersionDraft7)),
+	p1("if", constraintIf, vfrom(VersionDraft7)),
 	p2("items", constraintItems, allVersions|openAPI),
 	p1("maxContains", constraintMaxContains, vfrom(VersionDraft2019_09)),
 	p2("maxItems", constraintMaxItems, allVersions|openAPI),
@@ -122,7 +122,7 @@ var constraints = []*constraint{
 	p2("propertyNames", constraintPropertyNames, vfrom(VersionDraft6)),
 	p1("readOnly", constraintTODO, vfrom(VersionDraft7)|openAPI),
 	p3("required", constraintRequired, allVersions|openAPI),
-	p1("then", constraintTODO, vfrom(VersionDraft7)),
+	p1("then", constraintThen, vfrom(VersionDraft7)),
 	p2("title", constraintTitle, allVersions|openAPI),
 	p2("type", constraintType, allVersions|openAPI),
 	p1("unevaluatedItems", constraintTODO, vfrom(VersionDraft2019_09)),

encoding/jsonschema/constraints_combinator.go

@@ -148,3 +148,15 @@ func constraintNot(key string, n cue.Value, s *state) {
 		ast.NewList(subSchema),
 	))
 }
+
+func constraintIf(key string, n cue.Value, s *state) {
+	s.ifConstraint = s.schema(n)
+}
+
+func constraintThen(key string, n cue.Value, s *state) {
+	s.thenConstraint = s.schema(n)
+}
+
+func constraintElse(key string, n cue.Value, s *state) {
+	s.elseConstraint = s.schema(n)
+}

encoding/jsonschema/decode.go

@@ -385,6 +385,10 @@ type state struct {
 	minContains *uint64
 	maxContains *uint64
 
+	ifConstraint   ast.Expr
+	thenConstraint ast.Expr
+	elseConstraint ast.Expr
+
 	schemaVersion        Version
 	schemaVersionPresent bool
 
@@ -459,6 +463,7 @@ func (s *state) finalize() (e ast.Expr) {
 		s.addErr(errors.Newf(s.pos.Pos(), "constraints are not possible to satisfy"))
 		return bottom()
 	}
+	s.addIfThenElse()
 
 	conjuncts := []ast.Expr{}
 	disjuncts := []ast.Expr{}
@@ -608,6 +613,24 @@ outer:
 	return e
 }
 
+func (s *state) addIfThenElse() {
+	if s.ifConstraint == nil || (s.thenConstraint == nil && s.elseConstraint == nil) {
+		return
+	}
+	if s.thenConstraint == nil {
+		s.thenConstraint = top()
+	}
+	if s.elseConstraint == nil {
+		s.elseConstraint = top()
+	}
+	s.all.add(s.pos, ast.NewCall(
+		ast.NewIdent("matchIf"),
+		s.ifConstraint,
+		s.thenConstraint,
+		s.elseConstraint,
+	))
+}
+
 func (s *state) comment() *ast.CommentGroup {
 	// Create documentation.
 	doc := strings.TrimSpace(s.title)

encoding/jsonschema/external_teststats.txt

@@ -1,10 +1,10 @@
 # Generated by teststats. DO NOT EDIT
 v2:
-	schema extract (pass / total): 1040 / 1637 = 63.5%
-	tests (pass / total): 3378 / 7175 = 47.1%
-	tests on extracted schemas (pass / total): 3378 / 3792 = 89.1%
+	schema extract (pass / total): 1072 / 1637 = 65.5%
+	tests (pass / total): 3457 / 7175 = 48.2%
+	tests on extracted schemas (pass / total): 3457 / 3874 = 89.2%
 
 v3:
-	schema extract (pass / total): 1028 / 1637 = 62.8%
-	tests (pass / total): 3329 / 7175 = 46.4%
-	tests on extracted schemas (pass / total): 3329 / 3748 = 88.8%
+	schema extract (pass / total): 1060 / 1637 = 64.8%
+	tests (pass / total): 3408 / 7175 = 47.5%
+	tests on extracted schemas (pass / total): 3408 / 3830 = 89.0%

encoding/jsonschema/testdata/external/tests/draft2019-09/contains.json

@@ -201,10 +201,6 @@
 				"else": true
 			}
 		},
-		"skip": {
-			"v2": "extract error: keyword \"if\" not yet implemented (and 1 more errors)",
-			"v3": "extract error: keyword \"if\" not yet implemented (and 1 more errors)"
-		},
 		"tests": [
 			{
 				"description": "any non-empty array is valid",
@@ -213,18 +209,14 @@
 				],
 				"valid": true,
 				"skip": {
-					"v2": "could not compile schema",
-					"v3": "could not compile schema"
+					"v2": "6 errors in empty disjunction:\nconflicting values [\"foo\"] and {...} (mismatched types list and struct):\n    generated.cue:4:1\n    generated.cue:4:72\n    instance.json:1:1\nconflicting values bool and [\"foo\"] (mismatched types bool and list):\n    generated.cue:4:8\n    instance.json:1:1\nconflicting values null and [\"foo\"] (mismatched types null and list):\n    generated.cue:4:1\n    instance.json:1:1\nconflicting values number and [\"foo\"] (mismatched types number and list):\n    generated.cue:4:15\n    instance.json:1:1\nconflicting values string and [\"foo\"] (mismatched types string and list):\n    generated.cue:4:24\n    instance.json:1:1\nexplicit error (_|_ literal) in source:\n    generated.cue:4:58\n",
+					"v3": "conflicting values [\"foo\"] and {...} (mismatched types list and struct):\n    generated.cue:4:72\n    instance.json:1:1\nconflicting values bool and [\"foo\"] (mismatched types bool and list):\n    generated.cue:4:8\n    instance.json:1:1\nconflicting values null and [\"foo\"] (mismatched types null and list):\n    generated.cue:4:1\n    instance.json:1:1\nconflicting values number and [\"foo\"] (mismatched types number and list):\n    generated.cue:4:15\n    instance.json:1:1\nconflicting values string and [\"foo\"] (mismatched types string and list):\n    generated.cue:4:24\n    instance.json:1:1\nexplicit error (_|_ literal) in source:\n    generated.cue:4:58\n"
 				}
 			},
 			{
 				"description": "empty array is invalid",
 				"data": [],
-				"valid": false,
-				"skip": {
-					"v2": "could not compile schema",
-					"v3": "could not compile schema"
-				}
+				"valid": false
 			}
 		]
 	},