Support if-then-else #37

Project.toml

@@ -6,6 +6,7 @@ version = "1.3.0"
 Downloads = "f43a241f-c20a-4ad4-852c-f6b1247861c6"
 JSON = "682c06a0-de6a-54ab-a142-c8b1cf79cde6"
 JSON3 = "0f8b85d8-7281-11e9-16c2-39a750bddbf1"
+JSONPointer = "cc3ff66e-924d-4e6b-b111-1d9960e4bba9"
 URIs = "5c2747f8-b7ea-4ff2-ba2e-563bfd36b1d4"
 
 [compat]

src/JSONSchema.jl

@@ -8,6 +8,7 @@ module JSONSchema
 import Downloads
 import JSON
 import JSON3
+using JSONPointer
 import URIs
 
 export Schema, validate

src/schema.jl

@@ -3,18 +3,6 @@
 # Use of this source code is governed by an MIT-style license that can be found
 # in the LICENSE.md file or at https://opensource.org/licenses/MIT.
 
-# Transform escaped characters in JPaths back to their original value.
-function unescape_jpath(raw::String)
-    ret = replace(replace(raw, "~0" => "~"), "~1" => "/")
-    m = match(r"%([0-9A-F]{2})", ret)
-    if m !== nothing
-        for c in m.captures
-            ret = replace(ret, "%$(c)" => Char(parse(UInt8, "0x$(c)")))
-        end
-    end
-    return ret
-end
-
 function type_to_dict(x)
     return Dict(name => getfield(x, name) for name in fieldnames(typeof(x)))
 end
@@ -35,36 +23,6 @@ function update_id(uri::URIs.URI, s::String)
     return URIs.URI(; els...)
 end
 
-function get_element(schema, path::AbstractString)
-    for element in split(path, "/"; keepempty = false)
-        schema = _recurse_get_element(schema, unescape_jpath(String(element)))
-    end
-    return schema
-end
-
-function _recurse_get_element(schema::Any, ::String)
-    return error(
-        "unmanaged type in ref resolution $(typeof(schema)): $(schema).",
-    )
-end
-
-function _recurse_get_element(schema::AbstractDict, element::String)
-    if !haskey(schema, element)
-        error("missing property '$(element)' in $(schema).")
-    end
-    return schema[element]
-end
-
-function _recurse_get_element(schema::AbstractVector, element::String)
-    index = tryparse(Int, element)  # Remember that `index` is 0-indexed!
-    if index === nothing
-        error("expected integer array index instead of '$(element)'.")
-    elseif index >= length(schema)
-        error("item index $(index) is larger than array $(schema).")
-    end
-    return schema[index+1]
-end
-
 function get_remote_schema(uri::URIs.URI)
     io = IOBuffer()
     r = Downloads.request(string(uri); output = io, throw = false)
@@ -89,7 +47,8 @@ function find_ref(
     if path == "" || path == "#"  # This path refers to the root schema.
         return id_map[string(uri)]
     elseif startswith(path, "#/")  # This path is a JPointer.
-        return get_element(id_map[string(uri)], path[3:end])
+        p = JSONPointer.Pointer(path; shift_index = true)
+        return get_pointer(id_map[string(uri)], p)
     end
     uri = update_id(uri, path)
     els = type_to_dict(uri)
@@ -114,7 +73,8 @@ function find_ref(
             ).data
         end
     end
-    return get_element(id_map[string(uri2)], uri.fragment)
+    p = JSONPointer.Pointer(uri.fragment; shift_index = true)
+    return get_pointer(id_map[string(uri2)], p)
 end
 
 # Recursively find all "$ref" fields and resolve their path.

src/validation.jl

@@ -98,6 +98,12 @@ function _validate_entry(x, schema::Bool, path::String)
     return schema ? nothing : SingleIssue(x, path, "schema", schema)
 end
 
+"""
+    _resolve_refs(schema, explored_refs = Any[])
+
+Resolves any `"\$ref"` keys it encounters.
+Note: This is recursive function and will continue to resolve references until no more are found.
+"""
 function _resolve_refs(schema::AbstractDict, explored_refs = Any[schema])
     if !haskey(schema, "\$ref")
         return schema
@@ -160,10 +166,71 @@ function _validate(x, schema, ::Val{:not}, val, path::String)
 end
 
 # 9.2.2.1: if
-
+function _validate(x, schema, ::Val{:if}, val, path::String)
+    # ignore if without then or else
+    if haskey(schema, "then") || haskey(schema, "else")
+        ret = _if_then_else(x, schema, path)
+        return ret
+    end
+    return nothing
+end
 # 9.2.2.2: then
-
+function _validate(x, schema, ::Val{:then}, val, path::String)
+    # ignore then without if
+    if haskey(schema, "if")
+        ret = _if_then_else(x, schema, path)
+        return ret
+    end
+    return nothing
+end
 # 9.2.2.3: else
+function _validate(x, schema, ::Val{:else}, val, path::String)
+    # ignore else without if
+    if haskey(schema, "if")
+        ret = _if_then_else(x, schema, path)
+        return ret
+    end
+    return nothing
+end
+
+"""
+    _if_then_else(x, schema, path)
+
+The if, then and else keywords allow the application of a subschema based on the outcome of another schema. Details are in the link and the truth table is as follows:
+
+```
+┌─────┬──────┬──────┬────────┐
+│ if  │ then │ else │ result │       
+├─────┼──────┼──────┼────────┤ 
+│ T   │ T    │ n/a  │ T      │  
+│ T   │ F    │ n/a  │ F      │ 
+│ F   │ n/a  │ T    │ T      │ 
+│ F   │ n/a  │ F    │ F      │ 
+│ n/a │ n/a  │ n/a  │ T      │
+└─────┴──────┴──────┴────────┘
+https://json-schema.org/understanding-json-schema/reference/conditionals#ifthenelse
+```
+"""
+function _if_then_else(x, schema, path)
+    val_if = _validate(x, schema["if"], path)
+    val_then = if haskey(schema, "then")
+        _validate(x, schema["then"], path)
+    end
+    val_else = if haskey(schema, "else")
+        _validate(x, schema["else"], path)
+    end
+    if isnothing(val_if)
+        if isnothing(val_then) && isnothing(val_else)
+            return nothing
+        else
+            return val_then
+        end
+    end
+    if isa(val_if, SingleIssue)
+        return val_else
+    end
+    return nothing
+end
 
 ###
 ### Checks for Arrays.

test/runtests.jl

@@ -131,7 +131,7 @@ write(
 }]""",
 )
 
-@testset "Draft 4/6" begin
+@testset "Draft 4/6/7" begin
     # Note(odow): I didn't want to use a mutable reference like this for the web-server.
     # The obvious thing to do is to start a new server for each value of `draft_folder`,
     # however, shutting down the webserver asynchronously doesn't play well with
@@ -148,6 +148,7 @@ write(
     @testset "$(draft_folder)" for draft_folder in [
         "draft4",
         "draft6",
+        "draft7",
         basename(abspath(LOCAL_TEST_DIR)),
     ]
         test_dir = joinpath(SCHEMA_TEST_DIR, draft_folder)
@@ -190,6 +191,7 @@ end
     @testset "$(draft_folder)" for draft_folder in [
         "draft4",
         "draft6",
+        "draft7",
         basename(abspath(LOCAL_TEST_DIR)),
     ]
         test_dir = joinpath(SCHEMA_TEST_DIR, draft_folder)
@@ -265,7 +267,7 @@ end
 
 @testset "errors" begin
     @test_throws(
-        ErrorException("missing property 'Foo' in $(Dict{String,Any}())."),
+        KeyError("Foo"),
         JSONSchema.Schema("""{
             "type": "object",
             "properties": {"version": {"\$ref": "#/definitions/Foo"}},
@@ -274,23 +276,27 @@ end
     )
 
     @test_throws(
-        ErrorException("unmanaged type in ref resolution $(Int64): 1."),
+        ArgumentError(
+            "JSON pointer does not match the data-structure. I tried (and failed) to index 1 with the key: Foo",
+        ),
         JSONSchema.Schema("""{
             "type": "object",
             "properties": {"version": {"\$ref": "#/definitions/Foo"}},
             "definitions": 1
         }""")
     )
     @test_throws(
-        ErrorException("expected integer array index instead of 'Foo'."),
+        ArgumentError(
+            "JSON pointer does not match the data-structure. I tried (and failed) to index Any[1, 2] with the key: Foo",
+        ),
         JSONSchema.Schema("""{
             "type": "object",
             "properties": {"version": {"\$ref": "#/definitions/Foo"}},
             "definitions": [1, 2]
         }""")
     )
     @test_throws(
-        ErrorException("item index 3 is larger than array $(Any[1, 2])."),
+        BoundsError,
         JSONSchema.Schema("""{
             "type": "object",
             "properties": {"version": {"\$ref": "#/definitions/3"}},