Support patternProperties general case as a fallback (#22)

jviotti · web-flow · commit 33e17909d463 · 2026-04-06T11:24:35.000-04:00
Signed-off-by: Juan Cruz Viotti &lt;jv@jviotti.com&gt;
diff --git a/README.markdown b/README.markdown
@@ -32,7 +32,7 @@ to use a JSON Schema validator at runtime to enforce remaining constraints.
 | Applicator (2020-12) | `items` | Yes |
 | Applicator (2020-12) | `prefixItems` | Yes |
 | Applicator (2020-12) | `anyOf` | Yes |
-| Applicator (2020-12) | `patternProperties` | **PARTIAL** (Prefix patterns only) |
+| Applicator (2020-12) | `patternProperties` | **PARTIAL GIVEN LANGUAGE LIMITATIONS** |
 | Applicator (2020-12) | `propertyNames` | Ignored |
 | Applicator (2020-12) | `dependentSchemas` | Pending |
 | Applicator (2020-12) | `contains` | Ignored |
diff --git a/src/generator/typescript.cc b/src/generator/typescript.cc
@@ -1,7 +1,8 @@
 #include <sourcemeta/codegen/generator.h>
 
-#include <iomanip> // std::hex, std::setfill, std::setw
-#include <sstream> // std::ostringstream
+#include <algorithm> // std::ranges::any_of
+#include <iomanip>   // std::hex, std::setfill, std::setw
+#include <sstream>   // std::ostringstream
 
 namespace {
 
@@ -137,7 +138,12 @@ auto TypeScript::operator()(const IRObject &entry) -> void {
   }
 
   for (const auto &pattern_property : entry.pattern) {
-    this->output << "  [key: `" << pattern_property.prefix << "${string}`]: "
+    if (!pattern_property.prefix.has_value()) {
+      continue;
+    }
+
+    this->output << "  [key: `" << pattern_property.prefix.value()
+                 << "${string}`]: "
                  << mangle(this->prefix, pattern_property.pointer,
                            pattern_property.symbol, this->cache);
 
@@ -146,11 +152,11 @@ auto TypeScript::operator()(const IRObject &entry) -> void {
     // is a sub-prefix of another (i.e. "x-data-" starts with "x-"),
     // intersect the types so the constraint is satisfied
     for (const auto &other : entry.pattern) {
-      if (&other == &pattern_property) {
+      if (&other == &pattern_property || !other.prefix.has_value()) {
         continue;
       }
 
-      if (pattern_property.prefix.starts_with(other.prefix)) {
+      if (pattern_property.prefix.value().starts_with(other.prefix.value())) {
         this->output << " & "
                      << mangle(this->prefix, other.pointer, other.symbol,
                                this->cache);
@@ -160,9 +166,14 @@ auto TypeScript::operator()(const IRObject &entry) -> void {
     this->output << ";\n";
   }
 
+  const auto has_non_prefix_pattern{
+      std::ranges::any_of(entry.pattern, [](const auto &pattern_property) {
+        return !pattern_property.prefix.has_value();
+      })};
+
   if (allows_any_additional) {
     this->output << "  [key: string]: unknown | undefined;\n";
-  } else if (has_typed_additional) {
+  } else if (has_typed_additional || has_non_prefix_pattern) {
     // TypeScript index signatures must be a supertype of all property value
     // types. We use a union of all member types plus the additional properties
     // type plus undefined (for optional properties).
@@ -186,11 +197,14 @@ auto TypeScript::operator()(const IRObject &entry) -> void {
                    << " |\n";
     }
 
-    const auto &additional_type{std::get<IRType>(entry.additional)};
-    this->output << "    "
-                 << mangle(this->prefix, additional_type.pointer,
-                           additional_type.symbol, this->cache)
-                 << " |\n";
+    if (has_typed_additional) {
+      const auto &additional_type{std::get<IRType>(entry.additional)};
+      this->output << "    "
+                   << mangle(this->prefix, additional_type.pointer,
+                             additional_type.symbol, this->cache)
+                   << " |\n";
+    }
+
     this->output << "    undefined;\n";
   }
 
diff --git a/src/ir/include/sourcemeta/codegen/ir.h b/src/ir/include/sourcemeta/codegen/ir.h
@@ -64,7 +64,7 @@ struct IRObjectValue : IRType {
 
 /// @ingroup ir
 struct IRObjectPatternProperty : IRType {
-  std::string prefix;
+  std::optional<std::string> prefix;
 };
 
 /// @ingroup ir
diff --git a/src/ir/ir_default_compiler.h b/src/ir/ir_default_compiler.h
@@ -146,19 +146,18 @@ auto handle_object(const sourcemeta::core::JSON &schema,
           frame.traverse(sourcemeta::core::to_weak_pointer(pattern_pointer))};
       assert(pattern_location.has_value());
 
+      std::optional<std::string> prefix{std::nullopt};
       const auto regex{sourcemeta::core::to_regex(entry.first)};
-      if (!regex.has_value() ||
-          !std::holds_alternative<sourcemeta::core::RegexTypePrefix>(
+      if (regex.has_value() &&
+          std::holds_alternative<sourcemeta::core::RegexTypePrefix>(
               regex.value())) {
-        throw UnsupportedKeywordValueError(
-            schema, location.pointer, "patternProperties",
-            "Only prefix patterns are supported");
+        prefix = std::get<sourcemeta::core::RegexTypePrefix>(regex.value());
       }
 
       pattern.push_back(IRObjectPatternProperty{
           {.pointer = std::move(pattern_pointer),
            .symbol = symbol(frame, pattern_location.value().get())},
-          std::get<sourcemeta::core::RegexTypePrefix>(regex.value())});
+          std::move(prefix)});
     }
   }
 
diff --git a/test/e2e/typescript/2020-12/pattern_properties_additional_false/test.ts b/test/e2e/typescript/2020-12/pattern_properties_additional_false/test.ts
@@ -22,3 +22,9 @@ const test4: StrictExt = {
   // @ts-expect-error
   other: "value"
 };
+
+// Edge case: key is exactly the prefix with empty suffix
+const test5: StrictExt = {
+  name: "hello",
+  "x-": "value"
+};
diff --git a/test/e2e/typescript/2020-12/pattern_properties_empty_pattern/expected.d.ts b/test/e2e/typescript/2020-12/pattern_properties_empty_pattern/expected.d.ts
@@ -0,0 +1,16 @@
+export type EmptyPatternName = string;
+
+export type EmptyPattern = number;
+
+export type EmptyPatternAdditionalProperties = never;
+
+export interface _EmptyPattern {
+  "name"?: EmptyPatternName;
+  [key: string]:
+    // As a notable limitation, TypeScript requires index signatures
+    // to also include the types of all of its properties, so we must
+    // match a superset of what JSON Schema allows
+    EmptyPatternName |
+    EmptyPattern |
+    undefined;
+}
diff --git a/test/e2e/typescript/2020-12/pattern_properties_empty_pattern/options.json b/test/e2e/typescript/2020-12/pattern_properties_empty_pattern/options.json
@@ -0,0 +1,3 @@
+{
+  "defaultPrefix": "EmptyPattern"
+}
diff --git a/test/e2e/typescript/2020-12/pattern_properties_empty_pattern/schema.json b/test/e2e/typescript/2020-12/pattern_properties_empty_pattern/schema.json
@@ -0,0 +1,11 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "type": "object",
+  "properties": {
+    "name": { "type": "string" }
+  },
+  "patternProperties": {
+    "": { "type": "integer" }
+  },
+  "additionalProperties": false
+}
diff --git a/test/e2e/typescript/2020-12/pattern_properties_empty_pattern/test.ts b/test/e2e/typescript/2020-12/pattern_properties_empty_pattern/test.ts
@@ -0,0 +1,20 @@
+import { _EmptyPattern } from "./expected";
+
+// Empty regex matches everything, so all keys go through [key: string]
+// union (string | number | undefined)
+const test1: _EmptyPattern = {
+  name: "hello",
+  anything: 42
+};
+
+const test2: _EmptyPattern = {
+  name: "hello",
+  anything: "also valid"
+};
+
+// Boolean is not in the union
+const test3: _EmptyPattern = {
+  name: "hello",
+  // @ts-expect-error
+  flag: true
+};
diff --git a/test/e2e/typescript/2020-12/pattern_properties_full_hybrid/expected.d.ts b/test/e2e/typescript/2020-12/pattern_properties_full_hybrid/expected.d.ts
@@ -0,0 +1,25 @@
+export type HybridName = string;
+
+export type HybridAge = number;
+
+export type HybridX = string;
+
+export type Hybrid_09_id = number;
+
+export type HybridAdditionalProperties = boolean;
+
+export interface Hybrid {
+  "name": HybridName;
+  "age"?: HybridAge;
+  [key: `x-${string}`]: HybridX;
+  [key: string]:
+    // As a notable limitation, TypeScript requires index signatures
+    // to also include the types of all of its properties, so we must
+    // match a superset of what JSON Schema allows
+    HybridName |
+    HybridAge |
+    HybridX |
+    Hybrid_09_id |
+    HybridAdditionalProperties |
+    undefined;
+}
diff --git a/test/e2e/typescript/2020-12/pattern_properties_full_hybrid/options.json b/test/e2e/typescript/2020-12/pattern_properties_full_hybrid/options.json
@@ -0,0 +1,3 @@
+{
+  "defaultPrefix": "Hybrid"
+}
diff --git a/test/e2e/typescript/2020-12/pattern_properties_full_hybrid/schema.json b/test/e2e/typescript/2020-12/pattern_properties_full_hybrid/schema.json
@@ -0,0 +1,14 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "type": "object",
+  "properties": {
+    "name": { "type": "string" },
+    "age": { "type": "integer" }
+  },
+  "required": [ "name" ],
+  "patternProperties": {
+    "^x-": { "type": "string" },
+    "[0-9]+_id": { "type": "integer" }
+  },
+  "additionalProperties": { "type": "boolean" }
+}
diff --git a/test/e2e/typescript/2020-12/pattern_properties_full_hybrid/test.ts b/test/e2e/typescript/2020-12/pattern_properties_full_hybrid/test.ts
@@ -0,0 +1,59 @@
+import { Hybrid } from "./expected";
+
+// All features together
+const test1: Hybrid = {
+  name: "hello",
+  age: 30,
+  "x-custom": "extension",
+  "123_id": 42,
+  flag: true
+};
+
+// Required name only
+const test2: Hybrid = {
+  name: "hello"
+};
+
+// Missing required name
+// @ts-expect-error
+const test3: Hybrid = {
+  age: 30
+};
+
+// Prefix pattern enforced: x- must be string, not number
+const test4: Hybrid = {
+  name: "hello",
+  // @ts-expect-error
+  "x-custom": 42
+};
+
+// Array is not in the union
+const test5: Hybrid = {
+  name: "hello",
+  // @ts-expect-error
+  extra: [ 1, 2, 3 ]
+};
+
+// Additional property with boolean (additionalProperties type)
+const test6: Hybrid = {
+  name: "hello",
+  flag: true
+};
+
+// JSON Schema would reject this (additionalProperties is boolean, not
+// number), but TypeScript allows it because the [key: string] union must
+// include all member and pattern types (number from "age" and the non-prefix
+// pattern). The generated types are always a superset of what JSON Schema
+// allows, never a subset.
+const test7: Hybrid = {
+  name: "hello",
+  extra: 42
+};
+
+// Template literal takes priority over permissive [key: string] union:
+// boolean is in the union but x- keys must be string
+const test8: Hybrid = {
+  name: "hello",
+  // @ts-expect-error
+  "x-custom": true
+};
diff --git a/test/e2e/typescript/2020-12/pattern_properties_mixed_prefix_and_fallback/expected.d.ts b/test/e2e/typescript/2020-12/pattern_properties_mixed_prefix_and_fallback/expected.d.ts
@@ -0,0 +1,8 @@
+export type MixedFallbackX = string;
+
+export type MixedFallback_09 = number;
+
+export interface MixedFallback {
+  [key: `x-${string}`]: MixedFallbackX;
+  [key: string]: unknown | undefined;
+}
diff --git a/test/e2e/typescript/2020-12/pattern_properties_mixed_prefix_and_fallback/options.json b/test/e2e/typescript/2020-12/pattern_properties_mixed_prefix_and_fallback/options.json
@@ -0,0 +1 @@
+{ "defaultPrefix": "MixedFallback" }
diff --git a/test/e2e/typescript/2020-12/pattern_properties_mixed_prefix_and_fallback/schema.json b/test/e2e/typescript/2020-12/pattern_properties_mixed_prefix_and_fallback/schema.json
@@ -0,0 +1,8 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "type": "object",
+  "patternProperties": {
+    "^x-": { "type": "string" },
+    "[0-9]+": { "type": "integer" }
+  }
+}
diff --git a/test/e2e/typescript/2020-12/pattern_properties_mixed_prefix_and_fallback/test.ts b/test/e2e/typescript/2020-12/pattern_properties_mixed_prefix_and_fallback/test.ts
@@ -0,0 +1,28 @@
+import { MixedFallback } from "./expected";
+
+// Prefix pattern enforced: x- key must be string
+const test1: MixedFallback = {
+  "x-foo": "hello"
+};
+
+// Prefix pattern enforced even with [key: string]: unknown fallback
+const test2: MixedFallback = {
+  // @ts-expect-error
+  "x-foo": 123
+};
+
+// Non-prefix pattern falls back to unknown, so any value works
+const test3: MixedFallback = {
+  "123": 42
+};
+
+const test4: MixedFallback = {
+  "123": "also fine"
+};
+
+// Mixed together
+const test5: MixedFallback = {
+  "x-custom": "hello",
+  "456": 99,
+  other: true
+};
diff --git a/test/e2e/typescript/2020-12/pattern_properties_non_prefix_additional_false/expected.d.ts b/test/e2e/typescript/2020-12/pattern_properties_non_prefix_additional_false/expected.d.ts
@@ -0,0 +1,16 @@
+export type StrictFallbackName = string;
+
+export type StrictFallbackAz_id = number;
+
+export type StrictFallbackAdditionalProperties = never;
+
+export interface StrictFallback {
+  "name"?: StrictFallbackName;
+  [key: string]:
+    // As a notable limitation, TypeScript requires index signatures
+    // to also include the types of all of its properties, so we must
+    // match a superset of what JSON Schema allows
+    StrictFallbackName |
+    StrictFallbackAz_id |
+    undefined;
+}
diff --git a/test/e2e/typescript/2020-12/pattern_properties_non_prefix_additional_false/options.json b/test/e2e/typescript/2020-12/pattern_properties_non_prefix_additional_false/options.json
@@ -0,0 +1 @@
+{ "defaultPrefix": "StrictFallback" }
diff --git a/test/e2e/typescript/2020-12/pattern_properties_non_prefix_additional_false/schema.json b/test/e2e/typescript/2020-12/pattern_properties_non_prefix_additional_false/schema.json
@@ -0,0 +1,11 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "type": "object",
+  "properties": {
+    "name": { "type": "string" }
+  },
+  "patternProperties": {
+    "[a-z]+_id": { "type": "integer" }
+  },
+  "additionalProperties": false
+}
diff --git a/test/e2e/typescript/2020-12/pattern_properties_non_prefix_additional_false/test.ts b/test/e2e/typescript/2020-12/pattern_properties_non_prefix_additional_false/test.ts
@@ -0,0 +1,30 @@
+import { StrictFallback } from "./expected";
+
+const test1: StrictFallback = {
+  name: "hello",
+  "user_id": 42
+};
+
+// JSON Schema would reject this (additionalProperties: false and "other"
+// does not match the pattern), but TypeScript allows it because the
+// [key: string] union must include all member types (string from "name"),
+// so any string value passes. The generated types are always a superset
+// of what JSON Schema allows, never a subset.
+const test2: StrictFallback = {
+  name: "hello",
+  other: "also string"
+};
+
+// Boolean is not in the union (string | number | undefined)
+const test3: StrictFallback = {
+  name: "hello",
+  // @ts-expect-error
+  flag: true
+};
+
+// Array is not in the union
+const test4: StrictFallback = {
+  name: "hello",
+  // @ts-expect-error
+  items: [ 1, 2, 3 ]
+};
diff --git a/test/e2e/typescript/2020-12/pattern_properties_non_prefix_fallback/expected.d.ts b/test/e2e/typescript/2020-12/pattern_properties_non_prefix_fallback/expected.d.ts
diff --git a/test/e2e/typescript/2020-12/pattern_properties_non_prefix_fallback/options.json b/test/e2e/typescript/2020-12/pattern_properties_non_prefix_fallback/options.json
diff --git a/test/e2e/typescript/2020-12/pattern_properties_non_prefix_fallback/schema.json b/test/e2e/typescript/2020-12/pattern_properties_non_prefix_fallback/schema.json
diff --git a/test/e2e/typescript/2020-12/pattern_properties_non_prefix_fallback/test.ts b/test/e2e/typescript/2020-12/pattern_properties_non_prefix_fallback/test.ts
diff --git a/test/e2e/typescript/2020-12/pattern_properties_non_prefix_only/expected.d.ts b/test/e2e/typescript/2020-12/pattern_properties_non_prefix_only/expected.d.ts
diff --git a/test/e2e/typescript/2020-12/pattern_properties_non_prefix_only/options.json b/test/e2e/typescript/2020-12/pattern_properties_non_prefix_only/options.json
diff --git a/test/e2e/typescript/2020-12/pattern_properties_non_prefix_only/schema.json b/test/e2e/typescript/2020-12/pattern_properties_non_prefix_only/schema.json
diff --git a/test/e2e/typescript/2020-12/pattern_properties_non_prefix_only/test.ts b/test/e2e/typescript/2020-12/pattern_properties_non_prefix_only/test.ts
diff --git a/test/ir/ir_2020_12_test.cc b/test/ir/ir_2020_12_test.cc

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+{`
	`2`	`+ "defaultPrefix": "EmptyPattern"`
	`3`	`+}`