Merge pull request #1068 from yurikhan/violationDetails

Schema violation details

doc/schema.md

@@ -8,7 +8,7 @@ RapidJSON implemented a JSON Schema validator for [JSON Schema Draft v4](http://
 
 [TOC]
 
-# Basic Usage {#BasicUsage}
+# Basic Usage {#Basic}
 
 First of all, you need to parse a JSON Schema into `Document`, and then compile the `Document` into a `SchemaDocument`.
 
@@ -52,11 +52,11 @@ Some notes:
 * One `SchemaDocument` can be referenced by multiple `SchemaValidator`s. It will not be modified by `SchemaValidator`s.
 * A `SchemaValidator` may be reused to validate multiple documents. To run it for other documents, call `validator.Reset()` first.
 
-# Validation during parsing/serialization {#ParsingSerialization}
+# Validation during parsing/serialization {#Fused}
 
 Unlike most JSON Schema validator implementations, RapidJSON provides a SAX-based schema validator. Therefore, you can parse a JSON from a stream while validating it on the fly. If the validator encounters a JSON value that invalidates the supplied schema, the parsing will be terminated immediately. This design is especially useful for parsing large JSON files.
 
-## DOM parsing {#DomParsing}
+## DOM parsing {#DOM}
 
 For using DOM in parsing, `Document` needs some preparation and finalizing tasks, in addition to receiving SAX events, thus it needs some work to route the reader, validator and the document. `SchemaValidatingReader` is a helper class that doing such work.
 
@@ -97,7 +97,7 @@ if (!reader.GetParseResult()) {
 }
 ~~~
 
-## SAX parsing {#SaxParsing}
+## SAX parsing {#SAX}
 
 For using SAX in parsing, it is much simpler. If it only need to validate the JSON without further processing, it is simply:
 
@@ -144,7 +144,7 @@ if (!d.Accept(validator)) {
 
 Of course, if your application only needs SAX-style serialization, it can simply send SAX events to `SchemaValidator` instead of `Writer`.
 
-# Remote Schema {#RemoteSchema}
+# Remote Schema {#Remote}
 
 JSON Schema supports [`$ref` keyword](http://spacetelescope.github.io/understanding-json-schema/structuring.html), which is a [JSON pointer](doc/pointer.md) referencing to a local or remote schema. Local pointer is prefixed with `#`, while remote pointer is an relative or absolute URI. For example:
 
@@ -176,7 +176,7 @@ The failed test is "changed scope ref invalid" of "change resolution scope" in `
 
 Besides, the `format` schema keyword for string values is ignored, since it is not required by the specification.
 
-## Regular Expression {#RegEx}
+## Regular Expression {#Regex}
 
 The schema keyword `pattern` and `patternProperties` uses regular expression to match the required pattern.
 
@@ -235,3 +235,271 @@ On a Mac Book Pro (2.8 GHz Intel Core i7), the following results are collected.
 |[`jayschema`](https://github.com/natesilva/jayschema)|0.1%|21 (± 1.14%)|
 
 That is, RapidJSON is about 1.5x faster than the fastest JavaScript library (ajv). And 1400x faster than the slowest one.
+
+# Schema violation reporting {#Reporting}
+
+(Unreleased as of 2017-09-20)
+
+When validating an instance against a JSON Schema,
+it is often desirable to report not only whether the instance is valid,
+but also the ways in which it violates the schema.
+
+The `SchemaValidator` class
+collects errors encountered during validation
+into a JSON `Value`.
+This error object can then be accessed as `validator.GetError()`.
+
+The structure of the error object is subject to change
+in future versions of RapidJSON,
+as there is no standard schema for violations.
+The details below this point are provisional only.
+
+## General provisions {#ReportingGeneral}
+
+Validation of an instance value against a schema
+produces an error value.
+The error value is always an object.
+An empty object `{}` indicates the instance is valid.
+
+* The name of each member
+  corresponds to the JSON Schema keyword that is violated.
+* The value is either an object describing a single violation,
+  or an array of such objects.
+
+Each violation object contains two string-valued members
+named `instanceRef` and `schemaRef`.
+`instanceRef` contains the URI fragment serialization
+of a JSON Pointer to the instance subobject
+in which the violation was detected.
+`schemaRef` contains the URI of the schema
+and the fragment serialization of a JSON Pointer
+to the subschema that was violated.
+
+Individual violation objects can contain other keyword-specific members.
+These are detailed further.
+
+For example, validating this instance:
+
+~~~json
+{"numbers": [1, 2, "3", 4, 5]}
+~~~
+
+against this schema:
+
+~~~json
+{
+  "type": "object",
+  "properties": {
+    "numbers": {"$ref": "numbers.schema.json"}
+  }
+}
+~~~
+
+where `numbers.schema.json` refers
+(via a suitable `IRemoteSchemaDocumentProvider`)
+to this schema:
+
+~~~json
+{
+  "type": "array",
+  "items": {"type": "number"}
+}
+~~~
+
+produces the following error object:
+
+~~~json
+{
+  "type": {
+    "instanceRef": "#/numbers/2",
+    "schemaRef": "numbers.schema.json#/items",
+    "expected": ["number"],
+    "actual": "string"
+  }
+}
+~~~
+
+## Validation keywords for numbers {#Numbers}
+
+### multipleOf {#multipleof}
+
+* `expected`: required number strictly greater than 0.
+  The value of the `multipleOf` keyword specified in the schema.
+* `actual`: required number.
+  The instance value.
+
+### maximum {#maximum}
+
+* `expected`: required number.
+  The value of the `maximum` keyword specified in the schema.
+* `exclusiveMaximum`: optional boolean.
+  This will be true if the schema specified `"exclusiveMaximum": true`,
+  and will be omitted otherwise.
+* `actual`: required number.
+  The instance value.
+
+### minimum {#minimum}
+
+* `expected`: required number.
+  The value of the `minimum` keyword specified in the schema.
+* `exclusiveMinimum`: optional boolean.
+  This will be true if the schema specified `"exclusiveMinimum": true`,
+  and will be omitted otherwise.
+* `actual`: required number.
+  The instance value.
+
+## Validation keywords for strings {#Strings}
+
+### maxLength {#maxLength}
+
+* `expected`: required number greater than or equal to 0.
+  The value of the `maxLength` keyword specified in the schema.
+* `actual`: required string.
+  The instance value.
+
+### minLength {#minLength}
+
+* `expected`: required number greater than or equal to 0.
+  The value of the `minLength` keyword specified in the schema.
+* `actual`: required string.
+  The instance value.
+
+### pattern {#pattern}
+
+* `actual`: required string.
+  The instance value.
+
+(The expected pattern is not reported
+because the internal representation in `SchemaDocument`
+does not store the pattern in original string form.)
+
+## Validation keywords for arrays {#Arrays}
+
+### additionalItems {#additionalItems}
+
+This keyword is reported
+when the value of `items` schema keyword is an array,
+the value of `additionalItems` is `false`,
+and the instance is an array
+with more items than specified in the `items` array.
+
+* `disallowed`: required integer greater than or equal to 0.
+  The index of the first item that has no corresponding schema.
+
+### maxItems and minItems {#maxItems-minItems}
+
+* `expected`: required integer greater than or equal to 0.
+  The value of `maxItems` (respectively, `minItems`)
+  specified in the schema.
+* `actual`: required integer greater than or equal to 0.
+  Number of items in the instance array.
+
+### uniqueItems {#uniqueItems}
+
+* `duplicates`: required array
+  whose items are integers greater than or equal to 0.
+  Indices of items of the instance that are equal.
+
+(RapidJSON only reports the first two equal items,
+for performance reasons.)
+
+## Validation keywords for objects
+
+### maxProperties and minProperties {#maxProperties-minProperties}
+
+* `expected`: required integer greater than or equal to 0.
+  The value of `maxProperties` (respectively, `minProperties`)
+  specified in the schema.
+* `actual`: required integer greater than or equal to 0.
+  Number of properties in the instance object.
+
+### required {#required}
+
+* `missing`: required array of one or more unique strings.
+  The names of properties
+  that are listed in the value of the `required` schema keyword
+  but not present in the instance object.
+
+### additionalProperties {#additionalProperties}
+
+This keyword is reported
+when the schema specifies `additionalProperties: false`
+and the name of a property of the instance is
+neither listed in the `properties` keyword
+nor matches any regular expression in the `patternProperties` keyword.
+
+* `disallowed`: required string.
+  Name of the offending property of the instance.
+
+(For performance reasons,
+RapidJSON only reports the first such property encountered.)
+
+### dependencies {#dependencies}
+
+* `errors`: required object with one or more properties.
+  Names and values of its properties are described below.
+
+Recall that JSON Schema Draft 04 supports
+*schema dependencies*,
+where presence of a named *controlling* property
+requires the instance object to be valid against a subschema,
+and *property dependencies*,
+where presence of a controlling property
+requires other *dependent* properties to be also present.
+
+For a violated schema dependency,
+`errors` will contain a property
+with the name of the controlling property
+and its value will be the error object
+produced by validating the instance object
+against the dependent schema.
+
+For a violated property dependency,
+`errors` will contain a property
+with the name of the controlling property
+and its value will be an array of one or more unique strings
+listing the missing dependent properties.
+
+## Validation keywords for any instance type {#AnyTypes}
+
+### enum {#enum}
+
+This keyword has no additional properties
+beyond `instanceRef` and `schemaRef`.
+
+* The allowed values are not listed
+  because `SchemaDocument` does not store them in original form.
+* The violating value is not reported
+  because it might be unwieldy.
+
+If you need to report these details to your users,
+you can access the necessary information
+by following `instanceRef` and `schemaRef`.
+
+### type {#type}
+
+* `expected`: required array of one or more unique strings,
+  each of which is one of the seven primitive types
+  defined by the JSON Schema Draft 04 Core specification.
+  Lists the types allowed by the `type` schema keyword.
+* `actual`: required string, also one of seven primitive types.
+  The primitive type of the instance.
+
+### allOf, anyOf, and oneOf {#allOf-anyOf-oneOf}
+
+* `errors`: required array of at least one object.
+  There will be as many items as there are subschemas
+  in the `allOf`, `anyOf` or `oneOf` schema keyword, respectively.
+  Each item will be the error value
+  produced by validating the instance
+  against the corresponding subschema.
+
+For `allOf`, at least one error value will be non-empty.
+For `anyOf`, all error values will be non-empty.
+For `oneOf`, either all error values will be non-empty,
+or more than one will be empty.
+
+### not {#not}
+
+This keyword has no additional properties
+apart from `instanceRef` and `schemaRef`.

example/schemavalidator/schemavalidator.cpp

@@ -6,6 +6,7 @@
 #include "rapidjson/filereadstream.h"
 #include "rapidjson/schema.h"
 #include "rapidjson/stringbuffer.h"
+#include "rapidjson/prettywriter.h"
 
 using namespace rapidjson;
 
@@ -67,6 +68,11 @@ int main(int argc, char *argv[]) {
         sb.Clear();
         validator.GetInvalidDocumentPointer().StringifyUriFragment(sb);
         fprintf(stderr, "Invalid document: %s\n", sb.GetString());
+        // Detailed violation report is available as a JSON value
+        sb.Clear();
+        PrettyWriter<StringBuffer> w(sb);
+        validator.GetError().Accept(w);
+        fprintf(stderr, "Error report:\n%s\n", sb.GetString());
         return EXIT_FAILURE;
     }
 }

include/rapidjson/schema.h

@@ -17,6 +17,7 @@
 
 #include "document.h"
 #include "pointer.h"
+#include "stringbuffer.h"
 #include <cmath> // abs, floor
 
 #if !defined(RAPIDJSON_SCHEMA_USE_INTERNALREGEX)
@@ -157,6 +158,62 @@ public:
     virtual void FreeState(void* p) = 0;
 };
 
+///////////////////////////////////////////////////////////////////////////////
+// IValidationErrorHandler
+
+template <typename SchemaType>
+class IValidationErrorHandler {
+public:
+    typedef typename SchemaType::Ch Ch;
+    typedef typename SchemaType::SValue SValue;
+
+    virtual ~IValidationErrorHandler() {}
+
+    virtual void NotMultipleOf(int64_t actual, const SValue& expected) = 0;
+    virtual void NotMultipleOf(uint64_t actual, const SValue& expected) = 0;
+    virtual void NotMultipleOf(double actual, const SValue& expected) = 0;
+    virtual void AboveMaximum(int64_t actual, const SValue& expected, bool exclusive) = 0;
+    virtual void AboveMaximum(uint64_t actual, const SValue& expected, bool exclusive) = 0;
+    virtual void AboveMaximum(double actual, const SValue& expected, bool exclusive) = 0;
+    virtual void BelowMinimum(int64_t actual, const SValue& expected, bool exclusive) = 0;
+    virtual void BelowMinimum(uint64_t actual, const SValue& expected, bool exclusive) = 0;
+    virtual void BelowMinimum(double actual, const SValue& expected, bool exclusive) = 0;
+
+    virtual void TooLong(const Ch* str, SizeType length, SizeType expected) = 0;
+    virtual void TooShort(const Ch* str, SizeType length, SizeType expected) = 0;
+    virtual void DoesNotMatch(const Ch* str, SizeType length) = 0;
+
+    virtual void DisallowedItem(SizeType index) = 0;
+    virtual void TooFewItems(SizeType actualCount, SizeType expectedCount) = 0;
+    virtual void TooManyItems(SizeType actualCount, SizeType expectedCount) = 0;
+    virtual void DuplicateItems(SizeType index1, SizeType index2) = 0;
+
+    virtual void TooManyProperties(SizeType actualCount, SizeType expectedCount) = 0;
+    virtual void TooFewProperties(SizeType actualCount, SizeType expectedCount) = 0;
+    virtual void StartMissingProperties() = 0;
+    virtual void AddMissingProperty(const SValue& name) = 0;
+    virtual bool EndMissingProperties() = 0;
+    virtual void PropertyViolations(ISchemaValidator** subvalidators, SizeType count) = 0;
+    virtual void DisallowedProperty(const Ch* name, SizeType length) = 0;
+
+    virtual void StartDependencyErrors() = 0;
+    virtual void StartMissingDependentProperties() = 0;
+    virtual void AddMissingDependentProperty(const SValue& targetName) = 0;
+    virtual void EndMissingDependentProperties(const SValue& sourceName) = 0;
+    virtual void AddDependencySchemaError(const SValue& souceName, ISchemaValidator* subvalidator) = 0;
+    virtual bool EndDependencyErrors() = 0;
+
+    virtual void DisallowedValue() = 0;
+    virtual void StartDisallowedType() = 0;
+    virtual void AddExpectedType(const typename SchemaType::ValueType& expectedType) = 0;
+    virtual void EndDisallowedType(const typename SchemaType::ValueType& actualType) = 0;
+    virtual void NotAllOf(ISchemaValidator** subvalidators, SizeType count) = 0;
+    virtual void NoneOf(ISchemaValidator** subvalidators, SizeType count) = 0;
+    virtual void NotOneOf(ISchemaValidator** subvalidators, SizeType count) = 0;
+    virtual void Disallowed() = 0;
+};
+
+
 ///////////////////////////////////////////////////////////////////////////////
 // Hasher
 
@@ -261,6 +318,7 @@ template <typename SchemaDocumentType>
 struct SchemaValidationContext {
     typedef Schema<SchemaDocumentType> SchemaType;
     typedef ISchemaStateFactory<SchemaType> SchemaValidatorFactoryType;
+    typedef IValidationErrorHandler<SchemaType> ErrorHandlerType;
     typedef typename SchemaType::ValueType ValueType;
     typedef typename ValueType::Ch Ch;
 
@@ -270,8 +328,9 @@ struct SchemaValidationContext {
         kPatternValidatorWithAdditionalProperty
     };
 
-    SchemaValidationContext(SchemaValidatorFactoryType& f, const SchemaType* s) :
+    SchemaValidationContext(SchemaValidatorFactoryType& f, ErrorHandlerType& eh, const SchemaType* s) :
         factory(f),
+        error_handler(eh),
         schema(s),
         valueSchema(),
         invalidKeyword(),
@@ -311,6 +370,7 @@ struct SchemaValidationContext {
     }
 
     SchemaValidatorFactoryType& factory;
+    ErrorHandlerType& error_handler;
     const SchemaType* schema;
     const SchemaType* valueSchema;
     const Ch* invalidKeyword;
@@ -345,10 +405,12 @@ public:
     typedef SchemaValidationContext<SchemaDocumentType> Context;
     typedef Schema<SchemaDocumentType> SchemaType;
     typedef GenericValue<EncodingType, AllocatorType> SValue;
+    typedef IValidationErrorHandler<Schema> ErrorHandler;
     friend class GenericSchemaDocument<ValueType, AllocatorType>;
 
     Schema(SchemaDocumentType* schemaDocument, const PointerType& p, const ValueType& value, const ValueType& document, AllocatorType* allocator) :
         allocator_(allocator),
+        uri_(schemaDocument->GetURI(), *allocator),
         pointer_(p),
         typeless_(schemaDocument->GetTypeless()),
         enum_(),
@@ -598,6 +660,10 @@ public:
 #endif
     }
 
+    const SValue& GetURI() const {
+        return uri_;
+    }
+
     const PointerType& GetPointer() const {
         return pointer_;
     }
@@ -616,9 +682,11 @@ public:
                     context.valueSchema = additionalItemsSchema_;
                 else if (additionalItems_)
                     context.valueSchema = typeless_;
-                else
+                else {
+                    context.error_handler.DisallowedItem(context.arrayElementIndex);
                     RAPIDJSON_INVALID_KEYWORD_RETURN(GetItemsString());
                 }
+            }
             else
                 context.valueSchema = typeless_;
 
@@ -642,35 +710,45 @@ public:
                 }
 
             if (context.objectPatternValidatorType == Context::kPatternValidatorOnly) {
-                if (!patternValid)
+                if (!patternValid) {
+                    context.error_handler.PropertyViolations(context.patternPropertiesValidators, count);
                     RAPIDJSON_INVALID_KEYWORD_RETURN(GetPatternPropertiesString());
                 }
+            }
             else if (context.objectPatternValidatorType == Context::kPatternValidatorWithProperty) {
-                if (!patternValid || !otherValid)
+                if (!patternValid || !otherValid) {
+                    context.error_handler.PropertyViolations(context.patternPropertiesValidators, count + 1);
                     RAPIDJSON_INVALID_KEYWORD_RETURN(GetPatternPropertiesString());
                 }
-            else if (!patternValid && !otherValid) // kPatternValidatorWithAdditionalProperty)
+            }
+            else if (!patternValid && !otherValid) { // kPatternValidatorWithAdditionalProperty)
+                context.error_handler.PropertyViolations(context.patternPropertiesValidators, count + 1);
                 RAPIDJSON_INVALID_KEYWORD_RETURN(GetPatternPropertiesString());
             }
+        }
 
         if (enum_) {
             const uint64_t h = context.factory.GetHashCode(context.hasher);
             for (SizeType i = 0; i < enumCount_; i++)
                 if (enum_[i] == h)
                     goto foundEnum;
+            context.error_handler.DisallowedValue();
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetEnumString());
             foundEnum:;
         }
 
         if (allOf_.schemas)
             for (SizeType i = allOf_.begin; i < allOf_.begin + allOf_.count; i++)
-                if (!context.validators[i]->IsValid())
+                if (!context.validators[i]->IsValid()) {
+                    context.error_handler.NotAllOf(&context.validators[allOf_.begin], allOf_.count);
                     RAPIDJSON_INVALID_KEYWORD_RETURN(GetAllOfString());
+                }
         
         if (anyOf_.schemas) {
             for (SizeType i = anyOf_.begin; i < anyOf_.begin + anyOf_.count; i++)
                 if (context.validators[i]->IsValid())
                     goto foundAny;
+            context.error_handler.NoneOf(&context.validators[anyOf_.begin], anyOf_.count);
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetAnyOfString());
             foundAny:;
         }
@@ -679,30 +757,39 @@ public:
             bool oneValid = false;
             for (SizeType i = oneOf_.begin; i < oneOf_.begin + oneOf_.count; i++)
                 if (context.validators[i]->IsValid()) {
-                    if (oneValid)
+                    if (oneValid) {
+                        context.error_handler.NotOneOf(&context.validators[oneOf_.begin], oneOf_.count);
                         RAPIDJSON_INVALID_KEYWORD_RETURN(GetOneOfString());
-                    else
+                    } else
                         oneValid = true;
                 }
-            if (!oneValid)
+            if (!oneValid) {
+                context.error_handler.NotOneOf(&context.validators[oneOf_.begin], oneOf_.count);
                 RAPIDJSON_INVALID_KEYWORD_RETURN(GetOneOfString());
             }
+        }
 
-        if (not_ && context.validators[notValidatorIndex_]->IsValid())
+        if (not_ && context.validators[notValidatorIndex_]->IsValid()) {
+            context.error_handler.Disallowed();
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetNotString());
+        }
 
         return true;
     }
 
     bool Null(Context& context) const {
-        if (!(type_ & (1 << kNullSchemaType)))
+        if (!(type_ & (1 << kNullSchemaType))) {
+            DisallowedType(context, GetNullString());
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetTypeString());
+        }
         return CreateParallelValidator(context);
     }
     
     bool Bool(Context& context, bool) const {
-        if (!(type_ & (1 << kBooleanSchemaType)))
+        if (!(type_ & (1 << kBooleanSchemaType))) {
+            DisallowedType(context, GetBooleanString());
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetTypeString());
+        }
         return CreateParallelValidator(context);
     }
 
@@ -731,8 +818,10 @@ public:
     }
 
     bool Double(Context& context, double d) const {
-        if (!(type_ & (1 << kNumberSchemaType)))
+        if (!(type_ & (1 << kNumberSchemaType))) {
+            DisallowedType(context, GetNumberString());
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetTypeString());
+        }
 
         if (!minimum_.IsNull() && !CheckDoubleMinimum(context, d))
             return false;
@@ -747,28 +836,38 @@ public:
     }
     
     bool String(Context& context, const Ch* str, SizeType length, bool) const {
-        if (!(type_ & (1 << kStringSchemaType)))
+        if (!(type_ & (1 << kStringSchemaType))) {
+            DisallowedType(context, GetStringString());
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetTypeString());
+        }
 
         if (minLength_ != 0 || maxLength_ != SizeType(~0)) {
             SizeType count;
             if (internal::CountStringCodePoint<EncodingType>(str, length, &count)) {
-                if (count < minLength_)
+                if (count < minLength_) {
+                    context.error_handler.TooShort(str, length, minLength_);
                     RAPIDJSON_INVALID_KEYWORD_RETURN(GetMinLengthString());
-                if (count > maxLength_)
+                }
+                if (count > maxLength_) {
+                    context.error_handler.TooLong(str, length, maxLength_);
                     RAPIDJSON_INVALID_KEYWORD_RETURN(GetMaxLengthString());
                 }
             }
+        }
 
-        if (pattern_ && !IsPatternMatch(pattern_, str, length))
+        if (pattern_ && !IsPatternMatch(pattern_, str, length)) {
+            context.error_handler.DoesNotMatch(str, length);
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetPatternString());
+        }
 
         return CreateParallelValidator(context);
     }
 
     bool StartObject(Context& context) const {
-        if (!(type_ & (1 << kObjectSchemaType)))
+        if (!(type_ & (1 << kObjectSchemaType))) {
+            DisallowedType(context, GetObjectString());
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetTypeString());
+        }
 
         if (hasDependencies_ || hasRequired_) {
             context.propertyExist = static_cast<bool*>(context.factory.MallocState(sizeof(bool) * propertyCount_));
@@ -826,45 +925,65 @@ public:
             return true;
         }
 
-        if (context.patternPropertiesSchemaCount == 0) // patternProperties are not additional properties
+        if (context.patternPropertiesSchemaCount == 0) { // patternProperties are not additional properties
+            context.error_handler.DisallowedProperty(str, len);
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetAdditionalPropertiesString());
+        }
 
         return true;
     }
 
     bool EndObject(Context& context, SizeType memberCount) const {
-        if (hasRequired_)
+        if (hasRequired_) {
+            context.error_handler.StartMissingProperties();
             for (SizeType index = 0; index < propertyCount_; index++)
-                if (properties_[index].required)
+                if (properties_[index].required && !context.propertyExist[index])
-                    if (!context.propertyExist[index])
+                    context.error_handler.AddMissingProperty(properties_[index].name);
+            if (context.error_handler.EndMissingProperties())
                 RAPIDJSON_INVALID_KEYWORD_RETURN(GetRequiredString());
+        }
 
-        if (memberCount < minProperties_)
+        if (memberCount < minProperties_) {
+            context.error_handler.TooFewProperties(memberCount, minProperties_);
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetMinPropertiesString());
+        }
 
-        if (memberCount > maxProperties_)
+        if (memberCount > maxProperties_) {
+            context.error_handler.TooManyProperties(memberCount, maxProperties_);
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetMaxPropertiesString());
+        }
 
         if (hasDependencies_) {
-            for (SizeType sourceIndex = 0; sourceIndex < propertyCount_; sourceIndex++)
+            context.error_handler.StartDependencyErrors();
+            for (SizeType sourceIndex = 0; sourceIndex < propertyCount_; sourceIndex++) {
+                const Property& source = properties_[sourceIndex];
                 if (context.propertyExist[sourceIndex]) {
-                    if (properties_[sourceIndex].dependencies) {
+                    if (source.dependencies) {
+                        context.error_handler.StartMissingDependentProperties();
                         for (SizeType targetIndex = 0; targetIndex < propertyCount_; targetIndex++)
-                            if (properties_[sourceIndex].dependencies[targetIndex] && !context.propertyExist[targetIndex])
+                            if (source.dependencies[targetIndex] && !context.propertyExist[targetIndex])
-                                RAPIDJSON_INVALID_KEYWORD_RETURN(GetDependenciesString());
+                                context.error_handler.AddMissingDependentProperty(properties_[targetIndex].name);
+                        context.error_handler.EndMissingDependentProperties(source.name);
                     }
-                    else if (properties_[sourceIndex].dependenciesSchema)
+                    else if (source.dependenciesSchema) {
-                        if (!context.validators[properties_[sourceIndex].dependenciesValidatorIndex]->IsValid())
+                        ISchemaValidator* dependenciesValidator = context.validators[source.dependenciesValidatorIndex];
-                            RAPIDJSON_INVALID_KEYWORD_RETURN(GetDependenciesString());
+                        if (!dependenciesValidator->IsValid())
+                            context.error_handler.AddDependencySchemaError(source.name, dependenciesValidator);
                     }
                 }
+            }
+            if (context.error_handler.EndDependencyErrors())
+                RAPIDJSON_INVALID_KEYWORD_RETURN(GetDependenciesString());
+        }
 
         return true;
     }
 
     bool StartArray(Context& context) const {
-        if (!(type_ & (1 << kArraySchemaType)))
+        if (!(type_ & (1 << kArraySchemaType))) {
+            DisallowedType(context, GetArrayString());
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetTypeString());
+        }
 
         context.arrayElementIndex = 0;
         context.inArray = true;
@@ -875,11 +994,15 @@ public:
     bool EndArray(Context& context, SizeType elementCount) const {
         context.inArray = false;
         
-        if (elementCount < minItems_)
+        if (elementCount < minItems_) {
+            context.error_handler.TooFewItems(elementCount, minItems_);
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetMinItemsString());
+        }
         
-        if (elementCount > maxItems_)
+        if (elementCount > maxItems_) {
+            context.error_handler.TooManyItems(elementCount, maxItems_);
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetMaxItemsString());
+        }
 
         return true;
     }
@@ -1100,15 +1223,20 @@ private:
     }
 
     bool CheckInt(Context& context, int64_t i) const {
-        if (!(type_ & ((1 << kIntegerSchemaType) | (1 << kNumberSchemaType))))
+        if (!(type_ & ((1 << kIntegerSchemaType) | (1 << kNumberSchemaType)))) {
+            DisallowedType(context, GetIntegerString());
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetTypeString());
+        }
 
         if (!minimum_.IsNull()) {
             if (minimum_.IsInt64()) {
-                if (exclusiveMinimum_ ? i <= minimum_.GetInt64() : i < minimum_.GetInt64())
+                if (exclusiveMinimum_ ? i <= minimum_.GetInt64() : i < minimum_.GetInt64()) {
+                    context.error_handler.BelowMinimum(i, minimum_, exclusiveMinimum_);
                     RAPIDJSON_INVALID_KEYWORD_RETURN(GetMinimumString());
                 }
+            }
             else if (minimum_.IsUint64()) {
+                context.error_handler.BelowMinimum(i, minimum_, exclusiveMinimum_);
                 RAPIDJSON_INVALID_KEYWORD_RETURN(GetMinimumString()); // i <= max(int64_t) < minimum.GetUint64()
             }
             else if (!CheckDoubleMinimum(context, static_cast<double>(i)))
@@ -1117,9 +1245,11 @@ private:
 
         if (!maximum_.IsNull()) {
             if (maximum_.IsInt64()) {
-                if (exclusiveMaximum_ ? i >= maximum_.GetInt64() : i > maximum_.GetInt64())
+                if (exclusiveMaximum_ ? i >= maximum_.GetInt64() : i > maximum_.GetInt64()) {
+                    context.error_handler.AboveMaximum(i, maximum_, exclusiveMaximum_);
                     RAPIDJSON_INVALID_KEYWORD_RETURN(GetMaximumString());
                 }
+            }
             else if (maximum_.IsUint64()) { }
                 /* do nothing */ // i <= max(int64_t) < maximum_.GetUint64()
             else if (!CheckDoubleMaximum(context, static_cast<double>(i)))
@@ -1128,9 +1258,11 @@ private:
 
         if (!multipleOf_.IsNull()) {
             if (multipleOf_.IsUint64()) {
-                if (static_cast<uint64_t>(i >= 0 ? i : -i) % multipleOf_.GetUint64() != 0)
+                if (static_cast<uint64_t>(i >= 0 ? i : -i) % multipleOf_.GetUint64() != 0) {
+                    context.error_handler.NotMultipleOf(i, multipleOf_);
                     RAPIDJSON_INVALID_KEYWORD_RETURN(GetMultipleOfString());
                 }
+            }
             else if (!CheckDoubleMultipleOf(context, static_cast<double>(i)))
                 return false;
         }
@@ -1139,14 +1271,18 @@ private:
     }
 
     bool CheckUint(Context& context, uint64_t i) const {
-        if (!(type_ & ((1 << kIntegerSchemaType) | (1 << kNumberSchemaType))))
+        if (!(type_ & ((1 << kIntegerSchemaType) | (1 << kNumberSchemaType)))) {
+            DisallowedType(context, GetIntegerString());
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetTypeString());
+        }
 
         if (!minimum_.IsNull()) {
             if (minimum_.IsUint64()) {
-                if (exclusiveMinimum_ ? i <= minimum_.GetUint64() : i < minimum_.GetUint64())
+                if (exclusiveMinimum_ ? i <= minimum_.GetUint64() : i < minimum_.GetUint64()) {
+                    context.error_handler.BelowMinimum(i, minimum_, exclusiveMinimum_);
                     RAPIDJSON_INVALID_KEYWORD_RETURN(GetMinimumString());
                 }
+            }
             else if (minimum_.IsInt64())
                 /* do nothing */; // i >= 0 > minimum.Getint64()
             else if (!CheckDoubleMinimum(context, static_cast<double>(i)))
@@ -1155,20 +1291,26 @@ private:
 
         if (!maximum_.IsNull()) {
             if (maximum_.IsUint64()) {
-                if (exclusiveMaximum_ ? i >= maximum_.GetUint64() : i > maximum_.GetUint64())
+                if (exclusiveMaximum_ ? i >= maximum_.GetUint64() : i > maximum_.GetUint64()) {
+                    context.error_handler.AboveMaximum(i, maximum_, exclusiveMaximum_);
                     RAPIDJSON_INVALID_KEYWORD_RETURN(GetMaximumString());
                 }
-            else if (maximum_.IsInt64())
+            }
+            else if (maximum_.IsInt64()) {
+                context.error_handler.AboveMaximum(i, maximum_, exclusiveMaximum_);
                 RAPIDJSON_INVALID_KEYWORD_RETURN(GetMaximumString()); // i >= 0 > maximum_
+            }
             else if (!CheckDoubleMaximum(context, static_cast<double>(i)))
                 return false;
         }
 
         if (!multipleOf_.IsNull()) {
             if (multipleOf_.IsUint64()) {
-                if (i % multipleOf_.GetUint64() != 0)
+                if (i % multipleOf_.GetUint64() != 0) {
+                    context.error_handler.NotMultipleOf(i, multipleOf_);
                     RAPIDJSON_INVALID_KEYWORD_RETURN(GetMultipleOfString());
                 }
+            }
             else if (!CheckDoubleMultipleOf(context, static_cast<double>(i)))
                 return false;
         }
@@ -1177,14 +1319,18 @@ private:
     }
 
     bool CheckDoubleMinimum(Context& context, double d) const {
-        if (exclusiveMinimum_ ? d <= minimum_.GetDouble() : d < minimum_.GetDouble())
+        if (exclusiveMinimum_ ? d <= minimum_.GetDouble() : d < minimum_.GetDouble()) {
+            context.error_handler.BelowMinimum(d, minimum_, exclusiveMinimum_);
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetMinimumString());
+        }
         return true;
     }
 
     bool CheckDoubleMaximum(Context& context, double d) const {
-        if (exclusiveMaximum_ ? d >= maximum_.GetDouble() : d > maximum_.GetDouble())
+        if (exclusiveMaximum_ ? d >= maximum_.GetDouble() : d > maximum_.GetDouble()) {
+            context.error_handler.AboveMaximum(d, maximum_, exclusiveMaximum_);
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetMaximumString());
+        }
         return true;
     }
 
@@ -1192,11 +1338,29 @@ private:
         double a = std::abs(d), b = std::abs(multipleOf_.GetDouble());
         double q = std::floor(a / b);
         double r = a - q * b;
-        if (r > 0.0)
+        if (r > 0.0) {
+            context.error_handler.NotMultipleOf(d, multipleOf_);
             RAPIDJSON_INVALID_KEYWORD_RETURN(GetMultipleOfString());
+        }
         return true;
     }
 
+    void DisallowedType(Context& context, const ValueType& actualType) const {
+        ErrorHandler& eh = context.error_handler;
+        eh.StartDisallowedType();
+
+        if (type_ & (1 << kNullSchemaType)) eh.AddExpectedType(GetNullString());
+        if (type_ & (1 << kBooleanSchemaType)) eh.AddExpectedType(GetBooleanString());
+        if (type_ & (1 << kObjectSchemaType)) eh.AddExpectedType(GetObjectString());
+        if (type_ & (1 << kArraySchemaType)) eh.AddExpectedType(GetArrayString());
+        if (type_ & (1 << kStringSchemaType)) eh.AddExpectedType(GetStringString());
+
+        if (type_ & (1 << kNumberSchemaType)) eh.AddExpectedType(GetNumberString());
+        else if (type_ & (1 << kIntegerSchemaType)) eh.AddExpectedType(GetIntegerString());
+
+        eh.EndDisallowedType(actualType);
+    }
+
     struct Property {
         Property() : schema(), dependenciesSchema(), dependenciesValidatorIndex(), dependencies(), required(false) {}
         ~Property() { AllocatorType::Free(dependencies); }
@@ -1221,6 +1385,7 @@ private:
     };
 
     AllocatorType* allocator_;
+    SValue uri_;
     PointerType pointer_;
     const SchemaType* typeless_;
     uint64_t* enum_;
@@ -1331,6 +1496,7 @@ public:
     typedef typename EncodingType::Ch Ch;
     typedef internal::Schema<GenericSchemaDocument> SchemaType;
     typedef GenericPointer<ValueType, Allocator> PointerType;
+    typedef GenericValue<EncodingType, Allocator> URIType;
     friend class internal::Schema<GenericSchemaDocument>;
     template <typename, typename, typename>
     friend class GenericSchemaValidator;
@@ -1340,10 +1506,13 @@ public:
         Compile a JSON document into schema document.
 
         \param document A JSON document as source.
+        \param uri The base URI of this schema document for purposes of violation reporting.
+        \param uriLength Length of \c name, in code points.
         \param remoteProvider An optional remote schema document provider for resolving remote reference. Can be null.
         \param allocator An optional allocator instance for allocating memory. Can be null.
     */
-    explicit GenericSchemaDocument(const ValueType& document, IRemoteSchemaDocumentProviderType* remoteProvider = 0, Allocator* allocator = 0) :
+    explicit GenericSchemaDocument(const ValueType& document, const Ch* uri = 0, SizeType uriLength = 0,
+        IRemoteSchemaDocumentProviderType* remoteProvider = 0, Allocator* allocator = 0) :
         remoteProvider_(remoteProvider),
         allocator_(allocator),
         ownAllocator_(),
@@ -1355,8 +1524,11 @@ public:
         if (!allocator_)
             ownAllocator_ = allocator_ = RAPIDJSON_NEW(Allocator)();
 
+        Ch noUri[1] = {0};
+        uri_.SetString(uri ? uri : noUri, uriLength, *allocator_);
+
         typeless_ = static_cast<SchemaType*>(allocator_->Malloc(sizeof(SchemaType)));
-        new (typeless_) SchemaType(this, PointerType(), ValueType(kObjectType).Move(), ValueType(kObjectType).Move(), 0);
+        new (typeless_) SchemaType(this, PointerType(), ValueType(kObjectType).Move(), ValueType(kObjectType).Move(), allocator_);
 
         // Generate root schema, it will call CreateSchema() to create sub-schemas,
         // And call AddRefSchema() if there are $ref.
@@ -1394,7 +1566,8 @@ public:
         root_(rhs.root_),
         typeless_(rhs.typeless_),
         schemaMap_(std::move(rhs.schemaMap_)),
-        schemaRef_(std::move(rhs.schemaRef_))
+        schemaRef_(std::move(rhs.schemaRef_)),
+        uri_(std::move(rhs.uri_))
     {
         rhs.remoteProvider_ = 0;
         rhs.allocator_ = 0;
@@ -1416,6 +1589,8 @@ public:
         RAPIDJSON_DELETE(ownAllocator_);
     }
 
+    const URIType& GetURI() const { return uri_; }
+
     //! Get the root schema.
     const SchemaType& GetRoot() const { return *root_; }
 
@@ -1546,6 +1721,7 @@ private:
     SchemaType* typeless_;
     internal::Stack<Allocator> schemaMap_;  // Stores created Pointer -> Schemas
     internal::Stack<Allocator> schemaRef_;  // Stores Pointer from $ref and schema which holds the $ref
+    URIType uri_;
 };
 
 //! GenericSchemaDocument using Value type.
@@ -1574,13 +1750,17 @@ template <
     typename StateAllocator = CrtAllocator>
 class GenericSchemaValidator :
     public internal::ISchemaStateFactory<typename SchemaDocumentType::SchemaType>, 
-    public internal::ISchemaValidator
+    public internal::ISchemaValidator,
+    public internal::IValidationErrorHandler<typename SchemaDocumentType::SchemaType>
 {
 public:
     typedef typename SchemaDocumentType::SchemaType SchemaType;
     typedef typename SchemaDocumentType::PointerType PointerType;
     typedef typename SchemaType::EncodingType EncodingType;
+    typedef typename SchemaType::SValue SValue;
     typedef typename EncodingType::Ch Ch;
+    typedef GenericStringRef<Ch> StringRefType;
+    typedef GenericValue<EncodingType, StateAllocator> ValueType;
 
     //! Constructor without output handler.
     /*!
@@ -1602,6 +1782,9 @@ public:
         schemaStack_(allocator, schemaStackCapacity),
         documentStack_(allocator, documentStackCapacity),
         outputHandler_(0),
+        error_(kObjectType),
+        currentError_(),
+        missingDependents_(),
         valid_(true)
 #if RAPIDJSON_SCHEMA_VERBOSE
         , depth_(0)
@@ -1630,6 +1813,9 @@ public:
         schemaStack_(allocator, schemaStackCapacity),
         documentStack_(allocator, documentStackCapacity),
         outputHandler_(&outputHandler),
+        error_(kObjectType),
+        currentError_(),
+        missingDependents_(),
         valid_(true)
 #if RAPIDJSON_SCHEMA_VERBOSE
         , depth_(0)
@@ -1648,6 +1834,9 @@ public:
         while (!schemaStack_.Empty())
             PopSchema();
         documentStack_.Clear();
+        error_.SetObject();
+        currentError_.SetNull();
+        missingDependents_.SetNull();
         valid_ = true;
     }
 
@@ -1655,6 +1844,10 @@ public:
     // Implementation of ISchemaValidator
     virtual bool IsValid() const { return valid_; }
 
+    //! Gets the error object.
+    ValueType& GetError() { return error_; }
+    const ValueType& GetError() const { return error_; }
+
     //! Gets the JSON pointer pointed to the invalid schema.
     PointerType GetInvalidSchemaPointer() const {
         return schemaStack_.Empty() ? PointerType() : CurrentSchema().GetPointer();
@@ -1670,6 +1863,188 @@ public:
         return documentStack_.Empty() ? PointerType() : PointerType(documentStack_.template Bottom<Ch>(), documentStack_.GetSize() / sizeof(Ch));
     }
 
+    void NotMultipleOf(int64_t actual, const SValue& expected) {
+        AddNumberError(SchemaType::GetMultipleOfString(), ValueType(actual).Move(), expected);
+    }
+    void NotMultipleOf(uint64_t actual, const SValue& expected) {
+        AddNumberError(SchemaType::GetMultipleOfString(), ValueType(actual).Move(), expected);
+    }
+    void NotMultipleOf(double actual, const SValue& expected) {
+        AddNumberError(SchemaType::GetMultipleOfString(), ValueType(actual).Move(), expected);
+    }
+    void AboveMaximum(int64_t actual, const SValue& expected, bool exclusive) {
+        AddNumberError(SchemaType::GetMaximumString(), ValueType(actual).Move(), expected,
+            exclusive ? &SchemaType::GetExclusiveMaximumString : 0);
+    }
+    void AboveMaximum(uint64_t actual, const SValue& expected, bool exclusive) {
+        AddNumberError(SchemaType::GetMaximumString(), ValueType(actual).Move(), expected,
+            exclusive ? &SchemaType::GetExclusiveMaximumString : 0);
+    }
+    void AboveMaximum(double actual, const SValue& expected, bool exclusive) {
+        AddNumberError(SchemaType::GetMaximumString(), ValueType(actual).Move(), expected,
+            exclusive ? &SchemaType::GetExclusiveMaximumString : 0);
+    }
+    void BelowMinimum(int64_t actual, const SValue& expected, bool exclusive) {
+        AddNumberError(SchemaType::GetMinimumString(), ValueType(actual).Move(), expected,
+            exclusive ? &SchemaType::GetExclusiveMinimumString : 0);
+    }
+    void BelowMinimum(uint64_t actual, const SValue& expected, bool exclusive) {
+        AddNumberError(SchemaType::GetMinimumString(), ValueType(actual).Move(), expected,
+            exclusive ? &SchemaType::GetExclusiveMinimumString : 0);
+    }
+    void BelowMinimum(double actual, const SValue& expected, bool exclusive) {
+        AddNumberError(SchemaType::GetMinimumString(), ValueType(actual).Move(), expected,
+            exclusive ? &SchemaType::GetExclusiveMinimumString : 0);
+    }
+
+    void TooLong(const Ch* str, SizeType length, SizeType expected) {
+        AddNumberError(SchemaType::GetMaxLengthString(),
+            ValueType(str, length, GetStateAllocator()).Move(), SValue(expected).Move());
+    }
+    void TooShort(const Ch* str, SizeType length, SizeType expected) {
+        AddNumberError(SchemaType::GetMinLengthString(),
+            ValueType(str, length, GetStateAllocator()).Move(), SValue(expected).Move());
+    }
+    void DoesNotMatch(const Ch* str, SizeType length) {
+        currentError_.SetObject();
+        currentError_.AddMember(GetActualString(), ValueType(str, length, GetStateAllocator()).Move(), GetStateAllocator());
+        AddCurrentError(SchemaType::GetPatternString());
+    }
+
+    void DisallowedItem(SizeType index) {
+        currentError_.SetObject();
+        currentError_.AddMember(GetDisallowedString(), ValueType(index).Move(), GetStateAllocator());
+        AddCurrentError(SchemaType::GetAdditionalItemsString(), true);
+    }
+    void TooFewItems(SizeType actualCount, SizeType expectedCount) {
+        AddNumberError(SchemaType::GetMinItemsString(),
+            ValueType(actualCount).Move(), SValue(expectedCount).Move());
+    }
+    void TooManyItems(SizeType actualCount, SizeType expectedCount) {
+        AddNumberError(SchemaType::GetMaxItemsString(),
+            ValueType(actualCount).Move(), SValue(expectedCount).Move());
+    }
+    void DuplicateItems(SizeType index1, SizeType index2) {
+        ValueType duplicates(kArrayType);
+        duplicates.PushBack(index1, GetStateAllocator());
+        duplicates.PushBack(index2, GetStateAllocator());
+        currentError_.SetObject();
+        currentError_.AddMember(GetDuplicatesString(), duplicates, GetStateAllocator());
+        AddCurrentError(SchemaType::GetUniqueItemsString(), true);
+    }
+
+    void TooManyProperties(SizeType actualCount, SizeType expectedCount) {
+        AddNumberError(SchemaType::GetMaxPropertiesString(),
+            ValueType(actualCount).Move(), SValue(expectedCount).Move());
+    }
+    void TooFewProperties(SizeType actualCount, SizeType expectedCount) {
+        AddNumberError(SchemaType::GetMinPropertiesString(),
+            ValueType(actualCount).Move(), SValue(expectedCount).Move());
+    }
+    void StartMissingProperties() {
+        currentError_.SetArray();
+    }
+    void AddMissingProperty(const SValue& name) {
+        currentError_.PushBack(ValueType(name, GetStateAllocator()).Move(), GetStateAllocator());
+    }
+    bool EndMissingProperties() {
+        if (currentError_.Empty())
+            return false;
+        ValueType error(kObjectType);
+        error.AddMember(GetMissingString(), currentError_, GetStateAllocator());
+        currentError_ = error;
+        AddCurrentError(SchemaType::GetRequiredString());
+        return true;
+    }
+    void PropertyViolations(ISchemaValidator** subvalidators, SizeType count) {
+        for (SizeType i = 0; i < count; ++i)
+            MergeError(static_cast<GenericSchemaValidator*>(subvalidators[i])->GetError());
+    }
+    void DisallowedProperty(const Ch* name, SizeType length) {
+        currentError_.SetObject();
+        currentError_.AddMember(GetDisallowedString(), ValueType(name, length, GetStateAllocator()).Move(), GetStateAllocator());
+        AddCurrentError(SchemaType::GetAdditionalPropertiesString(), true);
+    }
+
+    void StartDependencyErrors() {
+        currentError_.SetObject();
+    }
+    void StartMissingDependentProperties() {
+        missingDependents_.SetArray();
+    }
+    void AddMissingDependentProperty(const SValue& targetName) {
+        missingDependents_.PushBack(ValueType(targetName, GetStateAllocator()).Move(), GetStateAllocator());
+    }
+    void EndMissingDependentProperties(const SValue& sourceName) {
+        if (!missingDependents_.Empty())
+            currentError_.AddMember(ValueType(sourceName, GetStateAllocator()).Move(),
+                missingDependents_, GetStateAllocator());
+    }
+    void AddDependencySchemaError(const SValue& sourceName, ISchemaValidator* subvalidator) {
+        currentError_.AddMember(ValueType(sourceName, GetStateAllocator()).Move(),
+            static_cast<GenericSchemaValidator*>(subvalidator)->GetError(), GetStateAllocator());
+    }
+    bool EndDependencyErrors() {
+        if (currentError_.ObjectEmpty())
+            return false;
+        ValueType error(kObjectType);
+        error.AddMember(GetErrorsString(), currentError_, GetStateAllocator());
+        currentError_ = error;
+        AddCurrentError(SchemaType::GetDependenciesString());
+        return true;
+    }
+
+    void DisallowedValue() {
+        currentError_.SetObject();
+        AddCurrentError(SchemaType::GetEnumString());
+    }
+    void StartDisallowedType() {
+        currentError_.SetArray();
+    }
+    void AddExpectedType(const typename SchemaType::ValueType& expectedType) {
+        currentError_.PushBack(ValueType(expectedType, GetStateAllocator()).Move(), GetStateAllocator());
+    }
+    void EndDisallowedType(const typename SchemaType::ValueType& actualType) {
+        ValueType error(kObjectType);
+        error.AddMember(GetExpectedString(), currentError_, GetStateAllocator());
+        error.AddMember(GetActualString(), ValueType(actualType, GetStateAllocator()).Move(), GetStateAllocator());
+        currentError_ = error;
+        AddCurrentError(SchemaType::GetTypeString());
+    }
+    void NotAllOf(ISchemaValidator** subvalidators, SizeType count) {
+        for (SizeType i = 0; i < count; ++i) {
+            MergeError(static_cast<GenericSchemaValidator*>(subvalidators[i])->GetError());
+        }
+    }
+    void NoneOf(ISchemaValidator** subvalidators, SizeType count) {
+        AddErrorArray(SchemaType::GetAnyOfString(), subvalidators, count);
+    }
+    void NotOneOf(ISchemaValidator** subvalidators, SizeType count) {
+        AddErrorArray(SchemaType::GetOneOfString(), subvalidators, count);
+    }
+    void Disallowed() {
+        currentError_.SetObject();
+        AddCurrentError(SchemaType::GetNotString());
+    }
+
+#define RAPIDJSON_STRING_(name, ...) \
+    static const StringRefType& Get##name##String() {\
+        static const Ch s[] = { __VA_ARGS__, '\0' };\
+        static const StringRefType v(s, static_cast<SizeType>(sizeof(s) / sizeof(Ch) - 1)); \
+        return v;\
+    }
+
+    RAPIDJSON_STRING_(InstanceRef, 'i', 'n', 's', 't', 'a', 'n', 'c', 'e', 'R', 'e', 'f')
+    RAPIDJSON_STRING_(SchemaRef, 's', 'c', 'h', 'e', 'm', 'a', 'R', 'e', 'f')
+    RAPIDJSON_STRING_(Expected, 'e', 'x', 'p', 'e', 'c', 't', 'e', 'd')
+    RAPIDJSON_STRING_(Actual, 'a', 'c', 't', 'u', 'a', 'l')
+    RAPIDJSON_STRING_(Disallowed, 'd', 'i', 's', 'a', 'l', 'l', 'o', 'w', 'e', 'd')
+    RAPIDJSON_STRING_(Missing, 'm', 'i', 's', 's', 'i', 'n', 'g')
+    RAPIDJSON_STRING_(Errors, 'e', 'r', 'r', 'o', 'r', 's')
+    RAPIDJSON_STRING_(Duplicates, 'd', 'u', 'p', 'l', 'i', 'c', 'a', 't', 'e', 's')
+
+#undef RAPIDJSON_STRING_
+
 #if RAPIDJSON_SCHEMA_VERBOSE
 #define RAPIDJSON_SCHEMA_HANDLE_BEGIN_VERBOSE_() \
 RAPIDJSON_MULTILINEMACRO_BEGIN\
@@ -1761,7 +2136,7 @@ RAPIDJSON_MULTILINEMACRO_END
 
     // Implementation of ISchemaStateFactory<SchemaType>
     virtual ISchemaValidator* CreateSchemaValidator(const SchemaType& root) {
-        return new (GetStateAllocator().Malloc(sizeof(GenericSchemaValidator))) GenericSchemaValidator(*schemaDocument_, root,
+        return new (GetStateAllocator().Malloc(sizeof(GenericSchemaValidator))) GenericSchemaValidator(*schemaDocument_, root, documentStack_.template Bottom<char>(), documentStack_.GetSize(),
 #if RAPIDJSON_SCHEMA_VERBOSE
         depth_ + 1,
 #endif
@@ -1804,6 +2179,7 @@ private:
     GenericSchemaValidator( 
         const SchemaDocumentType& schemaDocument,
         const SchemaType& root,
+        const char* basePath, size_t basePathSize,
 #if RAPIDJSON_SCHEMA_VERBOSE
         unsigned depth,
 #endif
@@ -1818,11 +2194,16 @@ private:
         schemaStack_(allocator, schemaStackCapacity),
         documentStack_(allocator, documentStackCapacity),
         outputHandler_(0),
+        error_(kObjectType),
+        currentError_(),
+        missingDependents_(),
         valid_(true)
 #if RAPIDJSON_SCHEMA_VERBOSE
         , depth_(depth)
 #endif
     {
+        if (basePath && basePathSize)
+            memcpy(documentStack_.template Push<char>(basePathSize), basePath, basePathSize);
     }
 
     StateAllocator& GetStateAllocator() {
@@ -1886,8 +2267,10 @@ private:
                 if (!a)
                     CurrentContext().arrayElementHashCodes = a = new (GetStateAllocator().Malloc(sizeof(HashCodeArray))) HashCodeArray(kArrayType);
                 for (typename HashCodeArray::ConstValueIterator itr = a->Begin(); itr != a->End(); ++itr)
-                    if (itr->GetUint64() == h)
+                    if (itr->GetUint64() == h) {
+                        DuplicateItems(static_cast<SizeType>(itr - a->Begin()), a->Size());
                         RAPIDJSON_INVALID_KEYWORD_RETURN(SchemaType::GetUniqueItemsString());
+                    }
                 a->PushBack(h, GetStateAllocator());
             }
         }
@@ -1916,7 +2299,7 @@ private:
         }
     }
 
-    RAPIDJSON_FORCEINLINE void PushSchema(const SchemaType& schema) { new (schemaStack_.template Push<Context>()) Context(*this, &schema); }
+    RAPIDJSON_FORCEINLINE void PushSchema(const SchemaType& schema) { new (schemaStack_.template Push<Context>()) Context(*this, *this, &schema); }
     
     RAPIDJSON_FORCEINLINE void PopSchema() {
         Context* c = schemaStack_.template Pop<Context>(1);
@@ -1927,6 +2310,70 @@ private:
         c->~Context();
     }
 
+    void AddErrorLocation(ValueType& result, bool parent) {
+        GenericStringBuffer<EncodingType> sb;
+        PointerType instancePointer = GetInvalidDocumentPointer();
+        ((parent && instancePointer.GetTokenCount() > 0)
+            ? PointerType(instancePointer.GetTokens(), instancePointer.GetTokenCount() - 1)
+            : instancePointer).StringifyUriFragment(sb);
+        ValueType instanceRef(sb.GetString(), static_cast<SizeType>(sb.GetSize() / sizeof(Ch)),
+            GetStateAllocator());
+        result.AddMember(GetInstanceRefString(), instanceRef, GetStateAllocator());
+        sb.Clear();
+        memcpy(sb.Push(CurrentSchema().GetURI().GetStringLength()),
+            CurrentSchema().GetURI().GetString(),
+            CurrentSchema().GetURI().GetStringLength() * sizeof(Ch));
+        GetInvalidSchemaPointer().StringifyUriFragment(sb);
+        ValueType schemaRef(sb.GetString(), static_cast<SizeType>(sb.GetSize() / sizeof(Ch)),
+            GetStateAllocator());
+        result.AddMember(GetSchemaRefString(), schemaRef, GetStateAllocator());
+    }
+
+    void AddError(ValueType& keyword, ValueType& error) {
+        typename ValueType::MemberIterator member = error_.FindMember(keyword);
+        if (member == error_.MemberEnd())
+            error_.AddMember(keyword, error, GetStateAllocator());
+        else {
+            if (member->value.IsObject()) {
+                ValueType errors(kArrayType);
+                errors.PushBack(member->value, GetStateAllocator());
+                member->value = errors;
+            }
+            member->value.PushBack(error, GetStateAllocator());
+        }
+    }
+
+    void AddCurrentError(const typename SchemaType::ValueType& keyword, bool parent = false) {
+        AddErrorLocation(currentError_, parent);
+        AddError(ValueType(keyword, GetStateAllocator(), false).Move(), currentError_);
+    }
+
+    void MergeError(ValueType& other) {
+        for (typename ValueType::MemberIterator it = other.MemberBegin(), end = other.MemberEnd(); it != end; ++it) {
+            AddError(it->name, it->value);
+        }
+    }
+
+    void AddNumberError(const typename SchemaType::ValueType& keyword, ValueType& actual, const SValue& expected,
+        const typename SchemaType::ValueType& (*exclusive)() = 0) {
+        currentError_.SetObject();
+        currentError_.AddMember(GetActualString(), actual, GetStateAllocator());
+        currentError_.AddMember(GetExpectedString(), ValueType(expected, GetStateAllocator()).Move(), GetStateAllocator());
+        if (exclusive)
+            currentError_.AddMember(ValueType(exclusive(), GetStateAllocator()).Move(), true, GetStateAllocator());
+        AddCurrentError(keyword);
+    }
+
+    void AddErrorArray(const typename SchemaType::ValueType& keyword,
+        ISchemaValidator** subvalidators, SizeType count) {
+        ValueType errors(kArrayType);
+        for (SizeType i = 0; i < count; ++i)
+            errors.PushBack(static_cast<GenericSchemaValidator*>(subvalidators[i])->GetError(), GetStateAllocator());
+        currentError_.SetObject();
+        currentError_.AddMember(GetErrorsString(), errors, GetStateAllocator());
+        AddCurrentError(keyword);
+    }
+
     const SchemaType& CurrentSchema() const { return *schemaStack_.template Top<Context>()->schema; }
     Context& CurrentContext() { return *schemaStack_.template Top<Context>(); }
     const Context& CurrentContext() const { return *schemaStack_.template Top<Context>(); }
@@ -1940,6 +2387,9 @@ private:
     internal::Stack<StateAllocator> schemaStack_;    //!< stack to store the current path of schema (BaseSchemaType *)
     internal::Stack<StateAllocator> documentStack_;  //!< stack to store the current path of validating document (Ch)
     OutputHandler* outputHandler_;
+    ValueType error_;
+    ValueType currentError_;
+    ValueType missingDependents_;
     bool valid_;
 #if RAPIDJSON_SCHEMA_VERBOSE
     unsigned depth_;
@@ -1971,13 +2421,14 @@ class SchemaValidatingReader {
 public:
     typedef typename SchemaDocumentType::PointerType PointerType;
     typedef typename InputStream::Ch Ch;
+    typedef GenericValue<SourceEncoding, StackAllocator> ValueType;
 
     //! Constructor
     /*!
         \param is Input stream.
         \param sd Schema document.
     */
-    SchemaValidatingReader(InputStream& is, const SchemaDocumentType& sd) : is_(is), sd_(sd), invalidSchemaKeyword_(), isValid_(true) {}
+    SchemaValidatingReader(InputStream& is, const SchemaDocumentType& sd) : is_(is), sd_(sd), invalidSchemaKeyword_(), error_(kObjectType), isValid_(true) {}
 
     template <typename Handler>
     bool operator()(Handler& handler) {
@@ -1990,11 +2441,13 @@ public:
             invalidSchemaPointer_ = PointerType();
             invalidSchemaKeyword_ = 0;
             invalidDocumentPointer_ = PointerType();
+            error_.SetObject();
         }
         else {
             invalidSchemaPointer_ = validator.GetInvalidSchemaPointer();
             invalidSchemaKeyword_ = validator.GetInvalidSchemaKeyword();
             invalidDocumentPointer_ = validator.GetInvalidDocumentPointer();
+            error_.CopyFrom(validator.GetError(), allocator_);
         }
 
         return parseResult_;
@@ -2005,6 +2458,7 @@ public:
     const PointerType& GetInvalidSchemaPointer() const { return invalidSchemaPointer_; }
     const Ch* GetInvalidSchemaKeyword() const { return invalidSchemaKeyword_; }
     const PointerType& GetInvalidDocumentPointer() const { return invalidDocumentPointer_; }
+    const ValueType& GetError() const { return error_; }
 
 private:
     InputStream& is_;
@@ -2014,6 +2468,8 @@ private:
     PointerType invalidSchemaPointer_;
     const Ch* invalidSchemaKeyword_;
     PointerType invalidDocumentPointer_;
+    StackAllocator allocator_;
+    ValueType error_;
     bool isValid_;
 };