Support prefix patternProperties

Signed-off-by: Juan Cruz Viotti <jv@jviotti.com>

Author: jviotti

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` | **CANNOT SUPPORT** |
+| Applicator (2020-12) | `patternProperties` | **PARTIAL** (Prefix patterns only) |
 | Applicator (2020-12) | `propertyNames` | Ignored |
 | Applicator (2020-12) | `dependentSchemas` | Pending |
 | Applicator (2020-12) | `contains` | Ignored |

src/generator/typescript.cc

@@ -101,7 +101,7 @@ auto TypeScript::operator()(const IRObject &entry) -> void {
       std::holds_alternative<bool>(entry.additional) &&
       std::get<bool>(entry.additional)};
 
-  if (has_typed_additional && entry.members.empty()) {
+  if (has_typed_additional && entry.members.empty() && entry.pattern.empty()) {
     const auto &additional_type{std::get<IRType>(entry.additional)};
     this->output << "export type " << type_name << " = Record<string, "
                  << mangle(this->prefix, additional_type.pointer,
@@ -110,7 +110,7 @@ auto TypeScript::operator()(const IRObject &entry) -> void {
     return;
   }
 
-  if (allows_any_additional && entry.members.empty()) {
+  if (allows_any_additional && entry.members.empty() && entry.pattern.empty()) {
     this->output << "export type " << type_name
                  << " = Record<string, unknown>;\n";
     return;
@@ -136,6 +136,30 @@ auto TypeScript::operator()(const IRObject &entry) -> void {
                  << ";\n";
   }
 
+  for (const auto &pattern_property : entry.pattern) {
+    this->output << "  [key: `" << pattern_property.prefix << "${string}`]: "
+                 << mangle(this->prefix, pattern_property.pointer,
+                           pattern_property.symbol, this->cache);
+
+    // TypeScript requires that a more specific index signature type is
+    // assignable to any less specific one that overlaps it. When a prefix
+    // 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) {
+        continue;
+      }
+
+      if (pattern_property.prefix.starts_with(other.prefix)) {
+        this->output << " & "
+                     << mangle(this->prefix, other.pointer, other.symbol,
+                               this->cache);
+      }
+    }
+
+    this->output << ";\n";
+  }
+
   if (allows_any_additional) {
     this->output << "  [key: string]: unknown | undefined;\n";
   } else if (has_typed_additional) {
@@ -155,6 +179,13 @@ auto TypeScript::operator()(const IRObject &entry) -> void {
                    << " |\n";
     }
 
+    for (const auto &pattern_property : entry.pattern) {
+      this->output << "    "
+                   << mangle(this->prefix, pattern_property.pointer,
+                             pattern_property.symbol, this->cache)
+                   << " |\n";
+    }
+
     const auto &additional_type{std::get<IRType>(entry.additional)};
     this->output << "    "
                  << mangle(this->prefix, additional_type.pointer,

src/ir/include/sourcemeta/codegen/ir.h

@@ -62,11 +62,17 @@ struct IRObjectValue : IRType {
   bool immutable;
 };
 
+/// @ingroup ir
+struct IRObjectPatternProperty : IRType {
+  std::string prefix;
+};
+
 /// @ingroup ir
 struct IRObject : IRType {
   // To preserve the user's ordering
   std::vector<std::pair<sourcemeta::core::JSON::String, IRObjectValue>> members;
   std::variant<bool, IRType> additional;
+  std::vector<IRObjectPatternProperty> pattern;
 };
 
 /// @ingroup ir

src/ir/ir_default_compiler.h

@@ -4,6 +4,7 @@
 #include <sourcemeta/codegen/ir.h>
 
 #include <sourcemeta/core/jsonschema.h>
+#include <sourcemeta/core/regex.h>
 
 #include <cassert>       // assert
 #include <string_view>   // std::string_view
@@ -77,7 +78,7 @@ auto handle_object(const sourcemeta::core::JSON &schema,
        // other properties. Therefore, we whitelist this, but we consider it to
        // be the responsability of the validator
        "additionalProperties", "minProperties", "maxProperties",
-       "propertyNames"});
+       "propertyNames", "patternProperties"});
 
   std::vector<std::pair<sourcemeta::core::JSON::String, IRObjectValue>> members;
 
@@ -133,10 +134,39 @@ auto handle_object(const sourcemeta::core::JSON &schema,
     }
   }
 
+  std::vector<IRObjectPatternProperty> pattern;
+  if (subschema.defines("patternProperties")) {
+    const auto &pattern_props{subschema.at("patternProperties")};
+    for (const auto &entry : pattern_props.as_object()) {
+      auto pattern_pointer{sourcemeta::core::to_pointer(location.pointer)};
+      pattern_pointer.push_back("patternProperties");
+      pattern_pointer.push_back(entry.first);
+
+      const auto pattern_location{
+          frame.traverse(sourcemeta::core::to_weak_pointer(pattern_pointer))};
+      assert(pattern_location.has_value());
+
+      const auto regex{sourcemeta::core::to_regex(entry.first)};
+      if (!regex.has_value() ||
+          !std::holds_alternative<sourcemeta::core::RegexTypePrefix>(
+              regex.value())) {
+        throw UnsupportedKeywordValueError(
+            schema, location.pointer, "patternProperties",
+            "Only prefix patterns are supported");
+      }
+
+      pattern.push_back(IRObjectPatternProperty{
+          {.pointer = std::move(pattern_pointer),
+           .symbol = symbol(frame, pattern_location.value().get())},
+          std::get<sourcemeta::core::RegexTypePrefix>(regex.value())});
+    }
+  }
+
   return IRObject{{.pointer = sourcemeta::core::to_pointer(location.pointer),
                    .symbol = symbol(frame, location)},
                   std::move(members),
-                  std::move(additional)};
+                  std::move(additional),
+                  std::move(pattern)};
 }
 
 auto handle_integer(const sourcemeta::core::JSON &schema,

test/e2e/typescript/2020-12/pattern_properties_additional_false/expected.d.ts

@@ -0,0 +1,10 @@
+export type StrictExtName = string;
+
+export type StrictExtX = string;
+
+export type StrictExtAdditionalProperties = never;
+
+export interface StrictExt {
+  "name"?: StrictExtName;
+  [key: `x-${string}`]: StrictExtX;
+}

test/e2e/typescript/2020-12/pattern_properties_additional_false/options.json

@@ -0,0 +1,3 @@
+{
+  "defaultPrefix": "StrictExt"
+}

test/e2e/typescript/2020-12/pattern_properties_additional_false/schema.json

@@ -0,0 +1,11 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "type": "object",
+  "properties": {
+    "name": { "type": "string" }
+  },
+  "patternProperties": {
+    "^x-": { "type": "string" }
+  },
+  "additionalProperties": false
+}

test/e2e/typescript/2020-12/pattern_properties_additional_false/test.ts

@@ -0,0 +1,24 @@
+import { StrictExt } from "./expected";
+
+const test1: StrictExt = {
+  name: "hello"
+};
+
+const test2: StrictExt = {
+  name: "hello",
+  "x-custom": "value"
+};
+
+// Wrong type for pattern property
+const test3: StrictExt = {
+  name: "hello",
+  // @ts-expect-error
+  "x-custom": 42
+};
+
+// Non-matching key should be rejected (additionalProperties: false)
+const test4: StrictExt = {
+  name: "hello",
+  // @ts-expect-error
+  other: "value"
+};

test/e2e/typescript/2020-12/pattern_properties_additional_true/expected.d.ts

@@ -0,0 +1,11 @@
+export type OpenExtName = string;
+
+export type OpenExtX = string;
+
+export type OpenExtAdditionalProperties = unknown;
+
+export interface OpenExt {
+  "name"?: OpenExtName;
+  [key: `x-${string}`]: OpenExtX;
+  [key: string]: unknown | undefined;
+}

test/e2e/typescript/2020-12/pattern_properties_additional_true/options.json

@@ -0,0 +1,3 @@
+{
+  "defaultPrefix": "OpenExt"
+}