From 3cd4ff83a253e098e6524df5be3a686727e4f50b Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sun, 28 Mar 2021 17:17:11 +0100
Subject: Initial commit of basis persistence

JSON parser lifted almost verbatim for libjsonpp running into some
custom code for populating ilt objects. Pretty minimal per object code
requirements.
---
 lib/jsonParse.h        |  43 ++++++++++++++
 lib/jsonParse.impl.cpp |  39 +++++++++++++
 lib/jsonParse.ll       | 156 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 238 insertions(+)
 create mode 100644 lib/jsonParse.h
 create mode 100644 lib/jsonParse.impl.cpp
 create mode 100644 lib/jsonParse.ll

(limited to 'lib')

diff --git a/lib/jsonParse.h b/lib/jsonParse.h
new file mode 100644
index 0000000..6b1249f
--- /dev/null
+++ b/lib/jsonParse.h
@@ -0,0 +1,43 @@
+#ifndef JSONFLEXLEXER_H
+#define JSONFLEXLEXER_H
+
+#ifndef FLEX_SCANNER
+#	define yyFlexLexer jsonBaseFlexLexer
+#	include <FlexLexer.h>
+#endif
+#include <cassert>
+#include <filesystem>
+#include <fstream>
+#include <memory>
+#include <stdexcept>
+#include <string>
+
+namespace json {
+	class jsonParser : public yyFlexLexer {
+	public:
+		using yyFlexLexer::yyFlexLexer;
+		int yylex() override;
+
+		static void appendEscape(const char *, std::string &);
+		static void appendEscape(unsigned long, std::string &);
+
+	protected:
+		virtual void BeginObject() = 0;
+		virtual void BeginArray() = 0;
+
+		virtual void PushBoolean(bool) = 0;
+		virtual void PushNumber(float) = 0;
+		virtual void PushNull() = 0;
+		virtual void PushText(std::string &&) = 0;
+		virtual void PushKey(std::string &&) = 0;
+
+		virtual void EndArray() = 0;
+		virtual void EndObject() = 0;
+
+		void LexerError(const char * msg) override;
+
+		std::string buf;
+	};
+}
+
+#endif
diff --git a/lib/jsonParse.impl.cpp b/lib/jsonParse.impl.cpp
new file mode 100644
index 0000000..27e73b4
--- /dev/null
+++ b/lib/jsonParse.impl.cpp
@@ -0,0 +1,39 @@
+#include "jsonParse.h"
+
+void
+json::jsonParser::LexerError(const char * msg)
+{
+	throw std::runtime_error(msg);
+}
+
+void
+json::jsonParser::appendEscape(const char * cphs, std::string & str)
+{
+	appendEscape(std::strtoul(cphs, nullptr, 16), str);
+}
+
+void
+json::jsonParser::appendEscape(unsigned long cp, std::string & str)
+{
+	if (cp <= 0x7F) {
+		str += cp;
+	}
+	else if (cp <= 0x7FF) {
+		str += (cp >> 6) + 192;
+		str += (cp & 63) + 128;
+	}
+	else if (0xd800 <= cp && cp <= 0xdfff) {
+		throw std::range_error("Invalid UTF-8 sequence");
+	}
+	else if (cp <= 0xFFFF) {
+		str += (cp >> 12) + 224;
+		str += ((cp >> 6) & 63) + 128;
+		str += (cp & 63) + 128;
+	}
+	else if (cp <= 0x10FFFF) {
+		str += (cp >> 18) + 240;
+		str += ((cp >> 12) & 63) + 128;
+		str += ((cp >> 6) & 63) + 128;
+		str += (cp & 63) + 128;
+	}
+}
diff --git a/lib/jsonParse.ll b/lib/jsonParse.ll
new file mode 100644
index 0000000..0fc27e9
--- /dev/null
+++ b/lib/jsonParse.ll
@@ -0,0 +1,156 @@
+%option batch
+%option c++
+%option noyywrap
+%option 8bit
+%option stack
+%option yylineno
+%option yyclass="json::jsonParser"
+%option prefix="jsonBase"
+
+%{
+#include <string>
+#include "jsonParse.h"
+#pragma GCC diagnostic ignored "-Wsign-compare"
+#pragma GCC diagnostic ignored "-Wimplicit-fallthrough"
+#ifdef __clang__
+#pragma clang diagnostic ignored "-Wnull-conversion"
+#endif
+%}
+
+beginobj "{"
+endobj "}"
+beginarray "["
+endarray "]"
+beginstr "\""
+endstr "\""
+true "true"
+false "false"
+null "null"
+number [-+]?[0-9]+(\.[0-9]+)?
+colon ":"
+separator ","
+escape "\\"
+text [^\\\"]*
+
+%x OBJECT_ITEM
+%x OBJECT_ITEM_OR_END
+%x OBJECT_NEXT
+%x ARRAY_ITEM
+%x ARRAY_NEXT
+%x COLON
+%x TEXT
+%x STRING
+%x ESCAPE
+
+%%
+
+<ARRAY_ITEM,INITIAL>{true} {
+	PushBoolean(true);
+	yy_pop_state();
+}
+
+<ARRAY_ITEM,INITIAL>{false} {
+	PushBoolean(false);
+	yy_pop_state();
+}
+
+<ARRAY_ITEM,INITIAL>{number} {
+	PushNumber(std::strtof(YYText(), NULL));
+	yy_pop_state();
+}
+
+<ARRAY_ITEM,INITIAL>{null} {
+	PushNull();
+	yy_pop_state();
+}
+
+<ARRAY_ITEM,INITIAL,OBJECT_ITEM,OBJECT_ITEM_OR_END>{beginstr} {
+	yy_push_state(STRING);
+}
+
+<ARRAY_ITEM,INITIAL>{beginobj} {
+	BeginObject();
+	BEGIN(OBJECT_ITEM_OR_END);
+}
+
+<ARRAY_ITEM,INITIAL>{beginarray} {
+	BeginArray();
+	BEGIN(ARRAY_NEXT);
+	yy_push_state(ARRAY_ITEM);
+}
+
+<STRING>{endstr} {
+	yy_pop_state();
+	switch (YY_START) {
+		case ARRAY_ITEM:
+		case INITIAL:
+			PushText(std::move(buf));
+			yy_pop_state();
+			break;
+		case OBJECT_ITEM:
+		case OBJECT_ITEM_OR_END:
+			PushKey(std::move(buf));
+			BEGIN(COLON);
+			break;
+	}
+	buf.clear();
+}
+
+<OBJECT_NEXT,OBJECT_ITEM_OR_END>{endobj} {
+	EndObject();
+	yy_pop_state();
+}
+
+<ARRAY_ITEM>{endarray} {
+	EndArray();
+	yy_pop_state();
+	yy_pop_state();
+}
+
+<ARRAY_NEXT>{endarray} {
+	EndArray();
+	yy_pop_state();
+}
+
+<COLON>{colon} {
+	BEGIN(OBJECT_NEXT);
+	yy_push_state(INITIAL);
+}
+
+<OBJECT_NEXT>{separator} {
+	BEGIN(OBJECT_ITEM);
+}
+
+<ARRAY_NEXT>{separator} {
+	yy_push_state(INITIAL);
+}
+
+<STRING>{escape} {
+	yy_push_state(ESCAPE);
+}
+
+<ESCAPE>"\"" { buf += "\""; yy_pop_state(); }
+<ESCAPE>"\\" { buf += "\\"; yy_pop_state(); }
+<ESCAPE>"/" { buf += "/"; yy_pop_state(); }
+<ESCAPE>"b" { buf += "\b"; yy_pop_state(); }
+<ESCAPE>"f" { buf += "\f"; yy_pop_state(); }
+<ESCAPE>"n" { buf += "\n"; yy_pop_state(); }
+<ESCAPE>"r" { buf += "\r"; yy_pop_state(); }
+<ESCAPE>"t" { buf += "\t"; yy_pop_state(); }
+
+<ESCAPE>"u"[0-9a-fA-Z]{4} {
+  appendEscape(YYText(), buf);
+	yy_pop_state();
+}
+
+<STRING>{text} {
+	buf += YYText();
+}
+
+<*>[ \t\r\n\f] {
+}
+
+%%
+
+// Make iwyu think unistd.h is required
+[[maybe_unused]]static auto x=getpid;
-- 
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