Add json.{h,cc} for pretty printing JSON

Avoids errors in trailing comma handling, broken indentation and
improper escaping that is common when building JSON by manually
concatenating strings.

kernel/json.h

@@ -0,0 +1,93 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2022  Jannis Harder <jix@yosyshq.com> <me@jix.one>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#ifndef JSON_H
+#define JSON_H
+
+#include "kernel/yosys.h"
+#include "libs/json11/json11.hpp"
+#include <functional>
+
+YOSYS_NAMESPACE_BEGIN
+
+using json11::Json;
+
+class PrettyJson
+{
+    enum Scope {
+        VALUE,
+        OBJECT_FIRST,
+        OBJECT,
+        ARRAY_FIRST,
+        ARRAY,
+    };
+
+    std::string newline_indent = "\n";
+    std::vector<std::function<void(const char *)>> targets;
+    std::vector<Scope> state = {VALUE};
+public:
+
+    void emit_to_log();
+    void append_to_string(std::string &target);
+
+    bool active() { return !targets.empty(); }
+
+    void line();
+    void raw(const char *raw_json);
+    void begin_object();
+    void begin_array();
+    void end_object();
+    void end_array();
+    void name(const char *name);
+    void begin_value();
+    void end_value();
+    void value_json(const Json &value);
+    void value(unsigned int value) { value_json(Json((int)value)); }
+    template<typename T>
+    void value(T &&value) { value_json(Json(std::forward<T>(value))); };
+
+    void entry_json(const char *name, const Json &value);
+    void entry(const char *name, unsigned int value) { entry_json(name, Json((int)value)); }
+    template<typename T>
+    void entry(const char *name, T &&value) { entry_json(name, Json(std::forward<T>(value))); };
+
+    template<typename T>
+    void object(const T &&values)
+    {
+        begin_object();
+        for (auto &item : values)
+            entry(item.first, item.second);
+        end_object();
+    }
+
+    template<typename T>
+    void array(const T &&values)
+    {
+        begin_object();
+        for (auto &item : values)
+            value(item);
+        end_object();
+    }
+};
+
+
+
+YOSYS_NAMESPACE_END
+
+#endif