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ae.utils.json: Add JsonOptions, non-string keys policy
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@CyberShadow
CyberShadow committed Nov 30, 2024
1 parent 084cc09 commit 048c38c
Showing 1 changed file with 105 additions and 20 deletions.
125 changes: 105 additions & 20 deletions utils/json.d
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,27 @@ import ae.utils.textout;

// ************************************************************************

/// JSON serialization / deserialization options
struct JsonOptions
{
/// What to do with associative arrays with non-string keys
enum NonStringKeys
{
/// Fail compilation.
error,

/// Serialize keys as-is - results in non-compliant JSON.
asIs,

/// Serialize keys as strings.
/// Note that this may result in multiple levels of quoting.
stringify,
}
NonStringKeys nonStringKeys = NonStringKeys.error; /// ditto
}

// ************************************************************************

/// Basic JSON writer.
struct JsonWriter(Output)
{
Expand Down Expand Up @@ -124,9 +145,8 @@ struct JsonWriter(Output)
output.putEx('}');
} ///

void putKey(in char[] key)
void endKey()
{
putString(key);
output.putEx(':');
} ///

Expand Down Expand Up @@ -202,10 +222,8 @@ struct PrettyJsonWriter(Output, alias indent = '\t', alias newLine = '\n', alias
jsonWriter.endObject();
} ///

void putKey(in char[] key)
void endKey()
{
putIndent();
putString(key);
output.putEx(pad, ':', pad);
} ///

Expand All @@ -217,7 +235,7 @@ struct PrettyJsonWriter(Output, alias indent = '\t', alias newLine = '\n', alias
}

/// Abstract JSON serializer based on `Writer`.
struct CustomJsonSerializer(Writer)
struct CustomJsonSerializer(Writer, JsonOptions options = JsonOptions.init)
{
Writer writer; /// Output.

Expand Down Expand Up @@ -282,7 +300,7 @@ struct CustomJsonSerializer(Writer)
}
}
else
static if (is(typeof(T.init.keys)) && is(typeof(T.init.values)) && is(typeof({string s = T.init.keys[0];})))
static if (is(typeof(T.init.keys)) && is(typeof(T.init.values)))
{
writer.beginObject();
bool first = true;
Expand All @@ -292,7 +310,17 @@ struct CustomJsonSerializer(Writer)
writer.putComma();
else
first = false;
writer.putKey(key);
static if (is(typeof({string s = T.init.keys[0];})))
writer.putValue(key);
else
static if (options.nonStringKeys == JsonOptions.NonStringKeys.asIs)
put(key);
else
static if (options.nonStringKeys == JsonOptions.NonStringKeys.stringify)
writer.putValue(key.toJson!options);
else
static assert(false, "Cannot serialize associative array with non-string key " ~ K.stringof);
writer.endKey();
put(value);
}
writer.endObject();
Expand All @@ -316,7 +344,8 @@ struct CustomJsonSerializer(Writer)
writer.putComma();
else
first = false;
writer.putKey(getJsonName!(T, v.tupleof[i].stringof[2..$]));
writer.putValue(getJsonName!(T, v.tupleof[i].stringof[2..$]));
writer.endKey();
put(field);
}
}
Expand Down Expand Up @@ -388,6 +417,14 @@ string toJson(T)(auto ref T v)
return serializer.writer.output.get();
}

/// ditto
string toJson(JsonOptions options, T)(auto ref T v)
{
CustomJsonSerializer!(JsonWriter!StringBuilder, options) serializer;
serializer.put(v);
return serializer.writer.output.get();
}

///
debug(ae_unittest) unittest
{
Expand Down Expand Up @@ -430,6 +467,14 @@ string toPrettyJson(T)(T v)
return serializer.writer.output.get();
}

/// ditto
string toPrettyJson(JsonOptions options, T)(T v)
{
CustomJsonSerializer!(PrettyJsonWriter!StringBuilder, options) serializer;
serializer.put(v);
return serializer.writer.output.get();
}

///
debug(ae_unittest) unittest
{
Expand Down Expand Up @@ -457,7 +502,7 @@ import std.conv;

import ae.utils.text;

private struct JsonParser(C)
private struct JsonParser(C, JsonOptions options = JsonOptions.init)
{
C[] s;
size_t p;
Expand Down Expand Up @@ -525,7 +570,7 @@ private struct JsonParser(C)
static if (isTuple!T)
readTuple!T(value);
else
static if (is(typeof(T.init.keys)) && is(typeof(T.init.values)) && is(typeof(T.init.keys[0])==string))
static if (is(typeof(T.init.keys)) && is(typeof(T.init.values)))
readAA!(T)(value);
else
static if (is(T==JSONFragment))
Expand Down Expand Up @@ -741,7 +786,7 @@ private struct JsonParser(C)
const(C)[] n;
auto start = p;
Unqual!C c = peek();
if (c == '"')
if (c == '"') // TODO: implicit type conversion should be optional
n = readSimpleString();
else
{
Expand Down Expand Up @@ -877,14 +922,27 @@ private struct JsonParser(C)

while (true)
{
auto jsonField = readString();
K jsonField;
static if (is(K == string))
jsonField = readString().to!K;
else
{
static if (options.nonStringKeys == JsonOptions.NonStringKeys.asIs)
read(jsonField);
else
static if (options.nonStringKeys == JsonOptions.NonStringKeys.stringify)
jsonField = readString().jsonParse!(K, options);
else
static assert(false, "Cannot parse associative array with non-string key " ~ K.stringof);
}

skipWhitespace();
expect(':');

// TODO: elide copy
typeof(v.values[0]) subvalue;
read(subvalue);
v[jsonField.to!K] = subvalue;
v[jsonField] = subvalue;

skipWhitespace();
if (peek()=='}')
Expand Down Expand Up @@ -986,13 +1044,16 @@ private struct JsonParser(C)
}

/// Parse the JSON in string `s` and deserialize it into an instance of `T`.
T jsonParse(T, C)(C[] s)
template jsonParse(T, JsonOptions options = JsonOptions.init)
{
auto parser = JsonParser!C(s);
mixin(exceptionContext(q{format("Error at position %d", parser.p)}));
T result;
parser.read!T(result);
return result;
T jsonParse(C)(C[] s)
{
auto parser = JsonParser!(C, options)(s);
mixin(exceptionContext(q{format("Error at position %d", parser.p)}));
T result;
parser.read!T(result);
return result;
}
}

debug(ae_unittest) unittest
Expand Down Expand Up @@ -1302,3 +1363,27 @@ debug(ae_unittest) unittest
assert(arr.toJson == `[1,true,"foo",[55]]`);
assert(arr.toJson.jsonParse!(JSONFragment[]) == arr);
}

// ************************************************************************

debug(ae_unittest) unittest
{
int[int] aa = [3: 4];
{
enum JsonOptions options = { nonStringKeys: JsonOptions.NonStringKeys.error };
static assert(!__traits(compiles, aa.toJson!options));
static assert(!__traits(compiles, "".jsonParse!(typeof(aa), options)));
}
{
enum JsonOptions options = { nonStringKeys: JsonOptions.NonStringKeys.asIs };
auto s = aa.toJson!options;
assert(s == `{3:4}`);
assert(s.jsonParse!(typeof(aa), options) == aa);
}
{
enum JsonOptions options = { nonStringKeys: JsonOptions.NonStringKeys.stringify };
auto s = aa.toJson!options;
assert(s == `{"3":4}`);
assert(s.jsonParse!(typeof(aa), options) == aa);
}
}

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