parser.c

/*
 * parser.c, libyaml parser binding for Lua
 * Written by Gary V. Vaughan, 2013
 *
 * Copyright (C) 2013-2022 Gary V. Vaughan
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "lyaml.h"

typedef struct {
   lua_State	 *L;
   yaml_parser_t  parser;
   yaml_event_t	  event;
   char		  validevent;
   int		  document_count;
} lyaml_parser;


static void
parser_delete_event (lyaml_parser *parser)
{
   if (parser->validevent)
   {
      yaml_event_delete (&parser->event);
      parser->validevent = 0;
   }
}

/* With the event result table on the top of the stack, insert
   a mark entry. */
static void
parser_set_mark (lua_State *L, const char *k, yaml_mark_t mark)
{
   lua_pushstring  (L, k);
   lua_createtable (L, 0, 3);
#define MENTRY(_s)	RAWSET_INTEGER(#_s, mark._s)
        MENTRY( index	);
        MENTRY( line	);
        MENTRY( column	);
#undef MENTRY
   lua_rawset (L, -3);
}

/* Push a new event table, pre-populated with shared elements. */
static void
parser_push_eventtable (lyaml_parser *parser, const char *v, int n)
{
   lua_State *L = parser->L;

   lua_createtable (L, 0, n + 3);
   RAWSET_STRING   ("type", v);
#define MENTRY(_s)	parser_set_mark (L, #_s, parser->event._s)
        MENTRY( start_mark	);
        MENTRY( end_mark	);
#undef MENTRY
}

static void
parse_STREAM_START (lyaml_parser *parser)
{
#define EVENTF(_f)	(parser->event.data.stream_start._f)
   lua_State *L = parser->L;
   const char *encoding;

   switch (EVENTF (encoding))
   {
#define MENTRY(_s)		\
      case YAML_##_s##_ENCODING: encoding = #_s; break

        MENTRY( ANY	);
        MENTRY( UTF8	);
        MENTRY( UTF16LE	);
        MENTRY( UTF16BE	);
#undef MENTRY

      default:
         lua_pushfstring (L, "invalid encoding %d", EVENTF (encoding));
         lua_error (L);
   }

   parser_push_eventtable (parser, "STREAM_START", 1);
   RAWSET_STRING ("encoding", encoding);
#undef EVENTF
}

/* With the tag list on the top of the stack, append TAG. */
static void
parser_append_tag (lua_State *L, yaml_tag_directive_t tag)
{
   lua_createtable (L, 0, 2);
#define MENTRY(_s)	RAWSET_STRING(#_s, tag._s)
        MENTRY( handle	);
        MENTRY( prefix	);
#undef MENTRY
   lua_rawseti (L, -2, lua_objlen (L, -2) + 1);
}

static void
parse_DOCUMENT_START (lyaml_parser *parser)
{
#define EVENTF(_f)	(parser->event.data.document_start._f)
   lua_State *L = parser->L;

   /* increment document count */
   parser->document_count++;

   parser_push_eventtable (parser, "DOCUMENT_START", 1);
   RAWSET_BOOLEAN ("implicit", EVENTF (implicit));

   /* version_directive = { major = M, minor = N } */
   if (EVENTF (version_directive))
   {
      lua_pushliteral (L, "version_directive");
      lua_createtable (L, 0, 2);
#define MENTRY(_s)	RAWSET_INTEGER(#_s, EVENTF (version_directive->_s))
        MENTRY( major	);
        MENTRY( minor	);
#undef MENTRY
      lua_rawset (L, -3);
   }

   /* tag_directives = { {handle = H1, prefix = P1}, ... } */
   if (EVENTF (tag_directives.start) &&
       EVENTF (tag_directives.end)) {
      yaml_tag_directive_t *cur;

      lua_pushliteral (L, "tag_directives");
      lua_newtable (L);
      for (cur = EVENTF (tag_directives.start);
           cur != EVENTF (tag_directives.end);
           cur = cur + 1)
      {
         parser_append_tag (L, *cur);
      }
      lua_rawset (L, -3);
   }
#undef EVENTF
}

static void
parse_DOCUMENT_END (lyaml_parser *parser)
{
#define EVENTF(_f)	(parser->event.data.document_end._f)
   lua_State *L = parser->L;

   parser_push_eventtable (parser, "DOCUMENT_END", 1);
   RAWSET_BOOLEAN ("implicit", EVENTF (implicit));
#undef EVENTF
}

static void
parse_ALIAS (lyaml_parser *parser)
{
#define EVENTF(_f)	(parser->event.data.alias._f)
   lua_State *L = parser->L;

   parser_push_eventtable (parser, "ALIAS", 1);
   RAWSET_EVENTF (anchor);
#undef EVENTF
}

static void
parse_SCALAR (lyaml_parser *parser)
{
#define EVENTF(_f)	(parser->event.data.scalar._f)
   lua_State *L = parser->L;
   const char *style;

   switch (EVENTF (style))
   {
#define MENTRY(_s)		\
      case YAML_##_s##_SCALAR_STYLE: style = #_s; break

        MENTRY( ANY		);
        MENTRY( PLAIN		);
        MENTRY( SINGLE_QUOTED	);
        MENTRY( DOUBLE_QUOTED	);
        MENTRY( LITERAL		);
        MENTRY( FOLDED		);
#undef MENTRY

      default:
         lua_pushfstring (L, "invalid sequence style %d", EVENTF (style));
         lua_error (L);
   }


   parser_push_eventtable (parser, "SCALAR", 6);
   RAWSET_EVENTF (anchor);
   RAWSET_EVENTF (tag);
   RAWSET_EVENTF (value);

   RAWSET_BOOLEAN ("plain_implicit", EVENTF (plain_implicit));
   RAWSET_BOOLEAN ("quoted_implicit", EVENTF (quoted_implicit));
   RAWSET_STRING  ("style", style);
#undef EVENTF
}

static void
parse_SEQUENCE_START (lyaml_parser *parser)
{
#define EVENTF(_f)	(parser->event.data.sequence_start._f)
   lua_State *L = parser->L;
   const char *style;

   switch (EVENTF (style))
   {
#define MENTRY(_s)		\
      case YAML_##_s##_SEQUENCE_STYLE: style = #_s; break

        MENTRY( ANY	);
        MENTRY( BLOCK	);
        MENTRY( FLOW	);
#undef MENTRY

      default:
         lua_pushfstring (L, "invalid sequence style %d", EVENTF (style));
         lua_error (L);
   }

   parser_push_eventtable (parser, "SEQUENCE_START", 4);
   RAWSET_EVENTF (anchor);
   RAWSET_EVENTF (tag);
   RAWSET_BOOLEAN ("implicit", EVENTF (implicit));
   RAWSET_STRING ("style", style);
#undef EVENTF
}

static void
parse_MAPPING_START (lyaml_parser *parser)
{
#define EVENTF(_f)	(parser->event.data.mapping_start._f)
   lua_State *L = parser->L;
   const char *style;

   switch (EVENTF (style))
   {
#define MENTRY(_s)		\
      case YAML_##_s##_MAPPING_STYLE: style = #_s; break

        MENTRY( ANY	);
        MENTRY( BLOCK	);
        MENTRY( FLOW	);
#undef MENTRY

      default:
         lua_pushfstring (L, "invalid mapping style %d", EVENTF (style));
         lua_error (L);
   }

   parser_push_eventtable (parser, "MAPPING_START", 4);
   RAWSET_EVENTF (anchor);
   RAWSET_EVENTF (tag);
   RAWSET_BOOLEAN ("implicit", EVENTF (implicit));
   RAWSET_STRING ("style", style);
#undef EVENTF
}

static void
parser_generate_error_message (lyaml_parser *parser)
{
   yaml_parser_t *P = &parser->parser;
   char buf[256];
   luaL_Buffer b;

   luaL_buffinit (parser->L, &b);
   luaL_addstring (&b, P->problem ? P->problem : "A problem");
   snprintf (buf, sizeof (buf), " at document: %d", parser->document_count);
   luaL_addstring (&b, buf);

   if (P->problem_mark.line || P->problem_mark.column)
   {
      snprintf (buf, sizeof (buf), ", line: %lu, column: %lu",
         (unsigned long) P->problem_mark.line + 1,
         (unsigned long) P->problem_mark.column + 1);
      luaL_addstring (&b, buf);
   }
   luaL_addstring (&b, "\n");

   if (P->context)
   {
      snprintf (buf, sizeof (buf), "%s at line: %lu, column: %lu\n",
         P->context,
         (unsigned long) P->context_mark.line + 1,
         (unsigned long) P->context_mark.column + 1);
      luaL_addstring (&b, buf);
   }

   luaL_pushresult (&b);
}

static int
event_iter (lua_State *L)
{
   lyaml_parser *parser = (lyaml_parser *)lua_touserdata(L, lua_upvalueindex(1));
   char *str;

   parser_delete_event (parser);
   if (yaml_parser_parse (&parser->parser, &parser->event) != 1)
   {
      parser_generate_error_message (parser);
      return lua_error (L);
   }

   parser->validevent = 1;

   lua_newtable    (L);
   lua_pushliteral (L, "type");

   switch (parser->event.type)
   {
      /* First the simple events, generated right here... */
#define MENTRY(_s)		\
      case YAML_##_s##_EVENT: parser_push_eventtable (parser, #_s, 0); break
         MENTRY( STREAM_END	);
         MENTRY( SEQUENCE_END   );
         MENTRY( MAPPING_END	);
#undef MENTRY

      /* ...then the complex events, generated by a function call. */
#define MENTRY(_s)		\
      case YAML_##_s##_EVENT: parse_##_s (parser); break
         MENTRY( STREAM_START	);
         MENTRY( DOCUMENT_START	);
         MENTRY( DOCUMENT_END	);
         MENTRY( ALIAS		);
         MENTRY( SCALAR		);
         MENTRY( SEQUENCE_START	);
         MENTRY( MAPPING_START	);
#undef MENTRY

      case YAML_NO_EVENT:
         lua_pushnil (L);
         break;
      default:
         lua_pushfstring  (L, "invalid event %d", parser->event.type);
         return lua_error (L);
   }

   return 1;
}

static int
parser_gc (lua_State *L)
{
   lyaml_parser *parser = (lyaml_parser *) lua_touserdata (L, 1);

   if (parser)
   {
      parser_delete_event (parser);
      yaml_parser_delete (&parser->parser);
   }
   return 0;
}

void
parser_init (lua_State *L)
{
   luaL_newmetatable(L, "lyaml.parser");
   lua_pushcfunction(L, parser_gc);
   lua_setfield(L, -2, "__gc");
}

int
Pparser (lua_State *L)
{
   lyaml_parser *parser;
   const unsigned char *str;

   /* requires a single string type argument */
   luaL_argcheck (L, lua_isstring (L, 1), 1, "must provide a string argument");
   str = (const unsigned char *) lua_tostring (L, 1);

   /* create a user datum to store the parser */
   parser = (lyaml_parser *) lua_newuserdata (L, sizeof (*parser));
   memset ((void *) parser, 0, sizeof (*parser));
   parser->L = L;

   /* set its metatable */
   luaL_getmetatable (L, "lyaml.parser");
   lua_setmetatable  (L, -2);

   /* try to initialize the parser */
   if (yaml_parser_initialize (&parser->parser) == 0)
      luaL_error (L, "cannot initialize parser for %s", str);
   yaml_parser_set_input_string (&parser->parser, str, lua_strlen (L, 1));

   /* create and return the iterator function, with the loader userdatum as
      its sole upvalue */
   lua_pushcclosure (L, event_iter, 1);
   return 1;
}