/**
 * mds — A micro-display server
 * Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include "make-tree.h"

#include "paths.h"

#include <limits.h>
#include <stdlib.h>
#include <libgen.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>


#ifndef DEBUG
# define DEBUG_PROC(statements)
#else
# define DEBUG_PROC(statements)  statements
#endif


/**
 * Print the current keyword stack, this is intended to
 * as a compiler debugging feature and should be used from
 * inside `DEBUG_PROC`
 */
#define PRINT_STACK					\
  do							\
    {							\
      size_t i = stack_ptr;				\
      fprintf(stderr, "stack {\n");			\
      while (i--)					\
	fprintf(stderr, "  %s\n", keyword_stack[i]);	\
      fprintf(stderr, "}\n");				\
    }							\
  while (0)


/**
 * Check whether a value is inside a closed range
 * 
 * @param   LOWER:¿T?  The lower bound, inclusive
 * @param   VALUE:¿T?  The value to test
 * @param   UPPER:¿T?  The upper bound, inclusive
 * @return  :int       1 if `LOWER` ≤ `VALUE` ≤ `UPPER`, otherwise 0
 */
#define in_range(LOWER, VALUE, UPPER)			\
  (((LOWER) <= (VALUE)) && ((VALUE) <= (UPPER)))


/**
 * Check whether a character is a valid callable name character, forward slash is accepted
 * 
 * @param   C:char  The character
 * @return  :int    Zero if `C` is a valid callable name character or a forward slash, otherwise 0
 */
#define is_name_char(C)									\
  (in_range('a', C, 'z') || in_range('A', C, 'Z') || strchr("0123456789_/", C))


/**
 * Pointer to the beginning of the current line
 */
#define LINE					\
  (result->source_code->lines[line_i])


/**
 * Update the tip of the stack to point to the address
 * of the current stack's tip's `next`-member
 */
#define NEXT							\
  tree_stack[stack_ptr] = &(tree_stack[stack_ptr][0]->next)


/**
 * Add an error to the error list
 * 
 * @param  ERROR_IS_IN_FILE:int           Whether the error is in the layout code
 * @param  SEVERITY:identifier            * in `MDS_KBDC_PARSE_ERROR_*` to indicate severity
 * @param  ...:const char*, ...           Error description format string and arguments
 * @scope  error:mds_kbdc_parse_error_t*  Variable where the new error will be stored
 */
#define NEW_ERROR(ERROR_IS_IN_FILE, SEVERITY, ...)				\
  NEW_ERROR_(result, SEVERITY, ERROR_IS_IN_FILE, line_i,			\
	     (size_t)(line - LINE), (size_t)(end - LINE), 1, __VA_ARGS__)


/**
 * Create a new node
 * 
 * @param  LOWERCASE:identifier  The keyword, for the node type, in lower case
 * @param  UPPERCASE:identifier  The keyword, for the node type, in upper case
 */
#define NEW_NODE(LOWERCASE, UPPERCASE)				\
  mds_kbdc_tree_##LOWERCASE##_t* node;				\
  fail_if (xcalloc(node, 1, mds_kbdc_tree_##LOWERCASE##_t));	\
  node->type = MDS_KBDC_TREE_TYPE_##UPPERCASE;			\
  node->loc_line  = line_i;					\
  node->loc_start = (size_t)(line - LINE);			\
  node->loc_end   = (size_t)(end  - LINE)


/**
 * Create a new node named `subnode`
 * 
 * @param  LOWERCASE:identifier  The keyword, for the node type, in lower case
 * @param  UPPERCASE:identifier  The keyword, for the node type, in upper case
 */
#define NEW_SUBNODE(LOWERCASE, UPPERCASE)				\
  mds_kbdc_tree_##LOWERCASE##_t* subnode;				\
  fail_if (xcalloc(subnode, 1, mds_kbdc_tree_##LOWERCASE##_t));		\
  subnode->type = MDS_KBDC_TREE_TYPE_##UPPERCASE;			\
  subnode->loc_line  = line_i;						\
  subnode->loc_start = (size_t)(line - LINE);				\
  subnode->loc_end   = (size_t)(end  - LINE)


/**
 * Update the tip of the tree stack with the current node
 * and change the pointer at the tip to the pointer to the
 * current node's down pointer
 * 
 * This is what should be done when a branch node has
 * been created and should be added to the result tree
 * 
 * @param  KEYWORD:const char*  The keyword for the current node's type
 */
#define BRANCH(KEYWORD)					\
  (*(tree_stack[stack_ptr]) = (mds_kbdc_tree_t*)node,	\
   tree_stack[stack_ptr + 1] = &(node->inner),		\
   keyword_stack[stack_ptr++] = KEYWORD)


/**
 * Update the tip of the tree stack with the current node
 * and change the pointer at the tip to the pointer to the
 * current node's next pointer
 * 
 * This is what should be done when a leaf node has been
 * created and should be added to the result tree
 */
#define LEAF						\
  (*(tree_stack[stack_ptr]) = (mds_kbdc_tree_t*)node,	\
   NEXT)


/**
 * Skip all blank spaces
 * 
 * @param  var:const char*  The variable
 */
#define SKIP_SPACES(var)		\
  while (*var && (*var == ' '))		\
    var++


/**
 * Check that there are no tokens after a keyword
 * 
 * @param  KEYWORD:const char*  The keyword
 */
#define NO_PARAMETERS(KEYWORD)		\
  fail_if (no_parameters(KEYWORD))


/**
 * Take next parameter, which should be a name of a callable,
 * and store it in the current node
 * 
 * @param  var:identifier  The name of the member variable, for the current
 *                         node, where the parameter should be stored
 */
#define NAMES_1(var)			\
  fail_if (names_1(&(node->var)))


/**
 * Suppress the next `line += strlen(line)`
 */
#define NO_JUMP			\
  (*end = prev_end_char,	\
   end = line,			\
   prev_end_char = *end,	\
   *end = '\0')


/**
 * Check whether a character ends a strings, whilst not being being a quote
 * 
 * @param  c:char  The character
 */
#define IS_END(c)	\
  strchr(" >}])", c)


/**
 * Take next parameter, which should be a string or numeral,
 * and store it in the current node
 * 
 * @param  var:identifier  The name of the member variable, for the current
 *                         node, where the parameter should be stored
 */
#define CHARS(var)			\
  fail_if (chars(&(node->var)))


/**
 * Test that there are no more parameters
 */
#define END						\
  do							\
    {							\
      SKIP_SPACES(line);				\
      if (*line)					\
	{						\
	  NEW_ERROR(1, ERROR, "too many parameters");	\
	  error->end = strlen(LINE);			\
	}						\
    }							\
  while (0)


/**
 * Test that the next parameter is in quotes
 */
#define QUOTES		\
  fail_if (quotes())


/**
 * Check that there is exactly one parameter, that it is in
 * quotes, and add it to the current node
 * 
 * @param  var:identifier  The name of the member variable, for the current
 *                         node, where the parameter should be stored
 */
#define QUOTES_1(var)	\
  do			\
    {			\
      QUOTES;		\
      CHARS(var);	\
      END;		\
    }			\
  while (0)


/**
 * Check that the next word is a specific keyword
 * 
 * @param  KEYWORD:const char*  The keyword
 */
#define TEST_FOR_KEYWORD(KEYWORD)	\
  fail_if (test_for_keyword(KEYWORD))


/**
 * Take next parameter, which should be a key combination or strings,
 * and store it in the current node
 * 
 * @param  var:identifier  The name of the member variable, for the current
 *                         node, where the parameter should be stored
 */
#define KEYS(var)		\
  fail_if (keys(&(node->var)))


/**
 * Take next parameter, which should be a key combination,
 * and store it in the current node
 * 
 * @param  var:identifier  The name of the member variable, for the current
 *                         node, where the parameter should be stored
 */
#define PURE_KEYS(var)			\
  fail_if (pure_keys(&(node->var)))



/**
 * Parse a sequence in a mapping
 * 
 * @param  mapseq:int  Whether this is a mapping sequence, otherwise
 *                     it is treated as macro call arguments
 */
#define SEQUENCE(mapseq)					\
  do /* for(;;) */						\
    {								\
      *end = prev_end_char;					\
      SKIP_SPACES(line);					\
      if ((*line == '\0') || (*line == (mapseq ? ':' : ')')))	\
	break;							\
      fail_if (sequence(mapseq, stack_orig));			\
    }								\
  while (1)


/**
 * Check that the scopes created in `SEQUENCE` has all been popped
 */
#define SEQUENCE_FULLY_POPPED			\
  fail_if (sequence_fully_popped(stack_orig))


/**
 * Create new leaf and update the stack accordingly
 * 
 * @param  LOWERCASE:identifier  The keyword, for the node type, in lower case
 * @param  UPPERCASE:identifier  The keyword, for the node type, in upper case
 * @param  PARSE:expression      Statement, without final semicolon, to retrieve members
 */
#define MAKE_LEAF(LOWERCASE, UPPERCASE, PARSE)		\
  do							\
    {							\
      NEW_NODE(LOWERCASE, UPPERCASE);			\
      PARSE;						\
      LEAF;						\
    }							\
  while (0)


/**
 * Create new branch and update the stack accordingly
 * 
 * @param  LOWERCASE:identifier  The keyword, for the node type, in lower case
 * @param  UPPERCASE:identifier  The keyword, for the node type, in upper case
 * @param  PARSE:expression      Statement, without final semicolon, to retrieve members
 */
#define MAKE_BRANCH(LOWERCASE, UPPERCASE, PARSE)	\
  do							\
    {							\
      NEW_NODE(LOWERCASE, UPPERCASE);			\
      PARSE;						\
      BRANCH(#LOWERCASE);				\
    }							\
  while (0)



/**
 * Variable whether the latest created error is stored
 */
static mds_kbdc_parse_error_t* error;

/**
 * Output parameter for the parsing result
 */
static mds_kbdc_parsed_t* restrict result;

/**
 * The head of the parsing-stack
 */
static size_t stack_ptr;

/**
 * The keyword portion of the parsing-stack
 */
static const char** restrict keyword_stack;

/**
 * The tree portion of the parsing-stack
 */
static mds_kbdc_tree_t*** restrict tree_stack;

/**
 * The index of the currently parsed line
 */
static size_t line_i = 0;

/**
 * Whether an array is currently being parsed
 */
static int in_array;

/**
 * The beginning of what has not get been parsed
 * on the current line
 */
static char* line = NULL;

/**
 * The end of what has been parsed on the current line
 */
static char* end = NULL;

/**
 * The previous value of `*end`
 */
static char prev_end_char;

/**
 * Pointer to the first non-whitespace character
 * on the current line
 */
static char* original;

/**
 * Whether it has been identified that the
 * current line has too few parameters
 */
static int too_few;



/***  Pre-parsing procedures.  ***/


/**
 * Get the pathname name of the parsed file
 * 
 * @param   filename  The filename of the parsed file
 * @return            The value the caller should return, or 1 if the caller should not return, -1 on error
 */
static int get_pathname(const char* restrict filename)
{
  char* cwd = NULL;
  int saved_errno;
  
  /* Get a non-relative pathname for the file, relative filenames
   * can be misleading as the program can have changed working
   * directory to be able to resolve filenames. */
  result->pathname = abspath(filename);
  if (result->pathname == NULL)
    {
      fail_if (errno != ENOENT);
      saved_errno = errno;
      fail_if (cwd = curpath(), cwd == NULL);
      result->pathname = strdup(filename);
      fail_if (result->pathname == NULL);
      NEW_ERROR_(result, ERROR, 0, 0, 0, 0, 1, "no such file or directory in ‘%s’", cwd);
      free(cwd);
      return 0;
    }
  
  /* Check that the file exists and can be read. */
  if (access(result->pathname, R_OK) < 0)
    {
      saved_errno = errno;
      NEW_ERROR_(result, ERROR, 0, 0, 0, 0, 0, NULL);
      error->description = strdup(strerror(saved_errno));
      fail_if (error->description == NULL);
      return 0;
    }
  
  return 1;
 fail:
  saved_errno = errno;
  free(cwd);
  return errno = saved_errno, -1;
}


/**
 * Allocate stacks needed to parse the tree
 * 
 * @return  Zero on success, -1 on error
 */
static int allocate_stacks(void)
{
  size_t max_line_length = 0, cur_line_length, line_n;
  
  /* The maximum line-length is needed because lines can have there own stacking,
   * like sequence mapping lines, additionally, let statements can have one array. */
  for (line_i = 0, line_n = result->source_code->line_count; line_i < line_n; line_i++)
    {
      cur_line_length = strlen(LINE);
      if (max_line_length < cur_line_length)
	max_line_length = cur_line_length;
    }
  
  fail_if (xmalloc(keyword_stack, line_n + max_line_length, const char*));
  fail_if (xmalloc(tree_stack, line_n + max_line_length + 1, mds_kbdc_tree_t**));

  return 0;
 fail:
  return -1;
}


/**
 * Read the file and simplify it a bit
 * 
 * @return  Zero on success, -1 on error
 */
static int read_source_code(void)
{
  /* Read the file and simplify it a bit. */
  fail_if (read_source_lines(result->pathname, result->source_code) < 0);
  
  return 0;
 fail:
  return -1;
}



/***  Post-parsing procedures.  ***/


/**
 * Check that a the file did not end prematurely by checking
 * that the stack has been fully popped
 * 
 * @return  Zero on success, -1 on error
 */
static int check_for_premature_end_of_file(void)
{
  /* Check that all scopes have been popped. */
  if (stack_ptr)
    {
      while (stack_ptr && keyword_stack[stack_ptr - 1] == NULL)
	stack_ptr--;
      if (stack_ptr)
	{
	  NEW_ERROR(0, ERROR, "premature end of file");
	  while (stack_ptr--)
	    {
	      if (keyword_stack[stack_ptr] == NULL)
		continue;
	      line_i = tree_stack[stack_ptr][0]->loc_line;
	      line = LINE + tree_stack[stack_ptr][0]->loc_start;
	      end  = LINE + tree_stack[stack_ptr][0]->loc_end;
	      if (!strcmp(keyword_stack[stack_ptr], "}"))
		NEW_ERROR(1, NOTE, "missing associated ‘%s’", keyword_stack[stack_ptr]);
	      else
		NEW_ERROR(1, NOTE, "missing associated ‘end %s’", keyword_stack[stack_ptr]);
	    }
	}
    }
  
  return 0;
 fail:
  return -1;
}


/**
 * Check whether the parsed file did not contain any code
 * and generate a warning if that is the case, comments
 * and whitespace is ignored
 * 
 * @return  Zero on success, -1 on error
 */
static int check_whether_file_is_empty(void)
{
  /* Warn about empty files. */
  if (result->tree == NULL)
    if (result->errors_ptr == 0)
      NEW_ERROR(0, WARNING, "file is empty");
  
  return 0;
 fail:
  return -1;
}



/***  Parsing subprocedures.  ***/


/**
 * Check that there are no tokens after a keyword
 * 
 * @param   keyword  The keyword
 * @return           Zero on success, -1 on error
 */
static int no_parameters(const char* restrict keyword)
{
  line += strlen(line);
  *end = prev_end_char, prev_end_char = '\0';
  SKIP_SPACES(line);
  if (*line)
    {
      end = line + strlen(line);
      NEW_ERROR(1, ERROR, "extra token after ‘%s’", keyword);
    }
  
  return 0;
 fail:
  return -1;
}



/**
 * Take next parameter, which should be a name of a callable,
 * and store it in the current node
 * 
 * @param   var  Address of the member variable, for the current
 *               node, where the parameter should be stored
 * @return       Zero on success, -1 on error
 */
static int names_1(char** restrict var)
{
  char* name_end;
  char* test;
  int stray_char = 0;
  char* end_end;
  
  line += strlen(line);
  *end = prev_end_char, prev_end_char = '\0';
  SKIP_SPACES(line);
  if (*line == '\0')
    {
      line = original, end = line + strlen(line);
      NEW_ERROR(1, ERROR, "a name is expected");
    }
  else
    {
      name_end = line;
      while (*name_end && is_name_char(*name_end))
	name_end++;
      if (*name_end && (*name_end != ' '))
	{
	  end_end = name_end + 1;
	  while ((*end_end & 0xC0) == 0x80)
	    end_end++;
	  prev_end_char = *end_end, *end_end = '\0';
	  NEW_ERROR(1, ERROR, "stray ‘%s’ character", name_end);
	  error->start = (size_t)(name_end - LINE);
	  error->end   = (size_t)(end_end  - LINE);
	  *end_end = prev_end_char;
	  stray_char = 1;
	}
      test = name_end;
      SKIP_SPACES(test);
      if (*test && !stray_char)
	{
	  NEW_ERROR(1, ERROR, "too many parameters");
	  error->start = (size_t)(test - LINE);
	  error->end   = strlen(LINE);
	}
      end = name_end;
      prev_end_char = *end;
      *end = '\0';
      fail_if ((*var = strdup(line)) == NULL);
    }
  
  return 0;
 fail:
  return -1;
}


/**
 * Take next parameter, which should be a string or numeral,
 * and store it in the current node
 * 
 * @param   var  Address of the member variable, for the current
 *               node, where the parameter should be stored
 * @return       Zero on success, -1 on error
 */
static int chars(char** restrict var)
{
  if (too_few)
    return 0;
  line += strlen(line);
  *end = prev_end_char, prev_end_char = '\0';
  SKIP_SPACES(line);
  if (*line == '\0')
    {
      line = original, end = line + strlen(line);
      NEW_ERROR(1, ERROR, "too few parameters");
      line = end, too_few = 1;
    }
  else
    {
      char* arg_end = line;
      char* call_end = arg_end;
      int escape = 0, quote = 0;
      while (*arg_end)
	{
	  char c = *arg_end++;
	  if      (escape)               escape = 0;
	  else if (arg_end <= call_end)  ;
	  else if (c == '\\')
	    {
	      escape = 1;
	      call_end = arg_end + get_end_of_call(arg_end, 0, strlen(arg_end));
	    }
	  else if (quote)                quote = (c != '"');
	  else if (IS_END(c))            { arg_end--; break; }
	  else                           quote = (c == '"');
	}
      prev_end_char = *arg_end, *arg_end = '\0', end = arg_end;
      fail_if ((*var = strdup(line)) == NULL);
      line = end;
    }
  
  return 0;
 fail:
  return -1;
}


/**
 * Test that the next parameter is in quotes
 * 
 * @return  Zero on success, -1 on error
 */
static int quotes(void)
{
  char* line_ = line;
  line += strlen(line);
  *end = prev_end_char;
  SKIP_SPACES(line);
  if (*line && (*line != '"'))
    {
      char* arg_end = line;
      SKIP_SPACES(arg_end);
      NEW_ERROR(1, ERROR, "parameter must be in quotes");
      error->end = (size_t)(arg_end - LINE);
    }
  *end = '\0';
  line = line_;
  
  return 0;
 fail:
  return -1;
}


/**
 * Check whether the currently line has unparsed parameters
 * 
 * @return  Whether the currently line has unparsed parameters, -1 on error
 */
static int have_more_parameters(void)
{
  if (too_few)
    return 0;
  line += strlen(line);
  *end = prev_end_char, prev_end_char = '\0';
  SKIP_SPACES(line);
  if (*line == '\0')
    {
      line = original, end = line + strlen(line);
      NEW_ERROR(1, ERROR, "too few parameters");
      line = end, too_few = 1;
      return 0;
    }
  return 1;
 fail:
  return -1;
}


/**
 * Check that the next word is a specific keyword
 * 
 * @param   keyword  The keyword
 * @return           Zero on success, -1 on error
 */
static int test_for_keyword(const char* restrict keyword)
{
  int ok, r = have_more_parameters();
  fail_if (r < 0);
  if (r == 0)
    return 0;
  
  ok = (strstr(line, keyword) == line);
  line += strlen(keyword);
  ok = ok && ((*line == '\0') || (*line == ' '));
  if (ok)
    {
      end = line;
      prev_end_char = *end, *end = '\0';
      return 0;
    }
  line -= strlen(keyword);
  end = line;
  SKIP_SPACES(end);
  prev_end_char = *end, *end = '\0';
  NEW_ERROR(1, ERROR, "expecting keyword ‘%s’", keyword);
  
  return 0;
 fail:
  return -1;
}


/**
 * Take next parameter, which should be a key combination or strings,
 * and store it in the current node
 * 
 * @param   var  Address of the member variable, for the current
 *               node, where the parameter should be stored
 * @return       Zero on success, -1 on error
 */
static int keys(mds_kbdc_tree_t** restrict var)
{
  char* arg_end;
  char* call_end;
  int r, escape = 0, quote = 0, triangle;
  r = have_more_parameters();
  fail_if (r < 0);
  if (r == 0)
    return 0;
  
  arg_end = line;
  call_end = arg_end;
  triangle = (*arg_end == '<');
  while (*arg_end)
    {
      char c = *arg_end++                ;
      if      (escape)                   escape = 0;
      else if (arg_end <= call_end)      ;
      else if (c == '\\')
	{
	  escape = 1;
	  call_end = arg_end + get_end_of_call(arg_end, 0, strlen(arg_end));
	}
      else if (quote)                    quote = (c != '"');
      else if (c == '\"')                quote = 1;
      else if (c == '>')                 triangle = 0;
      else if (IS_END(c) && !triangle)   { arg_end--; break; }
    }
  prev_end_char = *arg_end, *arg_end = '\0', end = arg_end;
  if (*line == '<')
    {
      NEW_SUBNODE(keys, KEYS);
      *var = (mds_kbdc_tree_t*)subnode;
      fail_if ((subnode->keys = strdup(line)) == NULL);
    }
  else
    {
      NEW_SUBNODE(string, STRING);
      *var = (mds_kbdc_tree_t*)subnode;
      fail_if ((subnode->string = strdup(line)) == NULL);
    }
  line = end;
  
  return 0;
 fail:
  return -1;
}



/**
 * Take next parameter, which should be a key combination,
 * and store it in the current node
 * 
 * @param   var  Address of the member variable, for the current
 *               node, where the parameter should be stored
 * @return       Zero on success, -1 on error
 */
static int pure_keys(char** restrict var)
{
  char* arg_end;
  char* call_end;
  int r, escape = 0, quote = 0, triangle;
  r = have_more_parameters();
  fail_if (r < 0);
  if (r == 0)
    return 0;
  
  arg_end = line;
  call_end = arg_end;
  triangle = (*arg_end == '<');
  while (*arg_end)
    {
      char c = *arg_end++                ;
      if      (escape)                   escape = 0;
      else if (arg_end <= call_end)      ;
      else if (c == '\\')
	{
	  escape = 1;
	  call_end = arg_end + get_end_of_call(arg_end, 0, strlen(arg_end));
	}
      else if (quote)                    quote = (c != '"');
      else if (c == '\"')                quote = 1;
      else if (c == '>')                 triangle = 0;
      else if (IS_END(c) && !triangle)   { arg_end--; break; }
    }
  prev_end_char = *arg_end, *arg_end = '\0';
  fail_if ((*var = strdup(line)) == NULL);
  end = arg_end, line = end;
  
  return 0;
 fail:
  return -1;
}


/**
 * Parse an element of a sequence in a mapping
 * 
 * @param   mapseq      Whether this is a mapping sequence, otherwise
 *                      it is treated as macro call arguments
 * @param   stack_orig  The size of the stack when `SEQUENCE` was called
 * @return              Zero on success, -1 on error
 */
static int sequence(int mapseq, size_t stack_orig)
{
  if (mapseq && (*line == '('))
    {
      NEW_NODE(unordered, UNORDERED);
      node->loc_end = node->loc_start + 1;
      BRANCH(")");
      line++;
    }
  else if (*line == '[')
    {
      NEW_NODE(alternation, ALTERNATION);
      node->loc_end = node->loc_start + 1;
      BRANCH("]");
      line++;
    }
  else if (*line == '.')
    {
      NEW_NODE(nothing, NOTHING);
      node->loc_end = node->loc_start + 1;
      LEAF;
      line++;
    }
  else if (strchr("])", *line))
    {
      end = line + 1;
      prev_end_char = *end, *end = '\0';
      if (stack_ptr == stack_orig)
	NEW_ERROR(1, ERROR, "runaway ‘%s’", line);
      else
	{
	  stack_ptr--;
	  if (strcmp(line, keyword_stack[stack_ptr]))
	    NEW_ERROR(1, ERROR, "expected ‘%s’ but got ‘%s’", keyword_stack[stack_ptr], line);
	  NEXT;
	}
      *end = prev_end_char;
      line++;
    }
  else if (*line == '<')
    {
      NEW_NODE(keys, KEYS);
      NO_JUMP;
      PURE_KEYS(keys);
      LEAF;
      node->loc_end = (size_t)(line - LINE);
    }
  else
    {
      NEW_NODE(string, STRING);
      NO_JUMP;
      CHARS(string);
      LEAF;	
      node->loc_end = (size_t)(line - LINE);
    }
  
  return 0;
 fail:
  return -1;
}


/**
 * Check that the scopes created in `SEQUENCE` has all been popped
 * 
 * @param  stack_orig  The size of the stack when `SEQUENCE` was called
 */
static int sequence_fully_popped(size_t stack_orig)
{
  if (stack_ptr == stack_orig)
    return 0;
  end = line + 1;
  NEW_ERROR(1, ERROR, "premature end of sequence");
  while (stack_ptr > stack_orig)
    {
      stack_ptr--;
      NEW_ERROR(1, NOTE, "missing associated ‘%s’", keyword_stack[stack_ptr]);
      error->start = tree_stack[stack_ptr][0]->loc_start;
      error->end   = tree_stack[stack_ptr][0]->loc_end;
    }
  
  return 0;
 fail:
  return -1;
}



/***  Parsing procedures.  ***/


/**
 * Parse an else- or else if-statement
 * 
 * @return  Zero on success, -1 on error, 1 if the caller should go to `redo`
 */
static int parse_else(void)
{
  size_t i;
  if (stack_ptr == 0)
    {
      NEW_ERROR(1, ERROR, "runaway ‘else’ statement");
      return 0;
    }
  line += strlen(line);
  *end = prev_end_char, prev_end_char = '\0';
  end = line + strlen(line);
  SKIP_SPACES(line);
  i = stack_ptr - 1;
  while (keyword_stack[i] == NULL)
    i--;
  if (strcmp(keyword_stack[i], "if"))
    {
      stack_ptr--;
      line = original, end = line + strlen(line);
      NEW_ERROR(1, ERROR, "runaway ‘else’ statement");
    }
  else if (*line == '\0')
    {
      /* else */
      mds_kbdc_tree_if_t* supernode = &(tree_stack[stack_ptr - 1][0]->if_);
      if (supernode->otherwise)
	{
	  line = strstr(LINE, "else");
	  end = line + 4, prev_end_char = *end;
	  NEW_ERROR(1, ERROR, "multiple ‘else’ statements");
	  mds_kbdc_tree_free(supernode->otherwise);
	  supernode->otherwise = NULL;
	}
      tree_stack[stack_ptr] = &(supernode->otherwise);
    }
  else if ((strstr(line, "if") == line) && ((line[2] == ' ') || (line[2] == '\0')))
    {
      /* else if */
      mds_kbdc_tree_if_t* supernode = &(tree_stack[stack_ptr - 1][0]->if_);
      NEW_NODE(if, IF);
      node->loc_end = node->loc_start + 2;
      end = line += 2, prev_end_char = *end, *end = '\0';
      CHARS(condition);
      END;
      tree_stack[stack_ptr] = &(supernode->otherwise);
      BRANCH(NULL);
    }
  else
    {
      NEW_ERROR(1, ERROR, "expecting nothing or ‘if’");
      stack_ptr--;
    }
  
  return 0;
 fail:
  return -1;
}


/**
 * Parse a for-statement
 * 
 * @return  Zero on success, -1 on error, 1 if the caller should go to `redo`
 */
static int parse_for(void)
{
  NEW_NODE(for, FOR);
  CHARS(first);
  TEST_FOR_KEYWORD("to");
  CHARS(last);
  TEST_FOR_KEYWORD("as");
  CHARS(variable);
  END;
  BRANCH("for");
  
  return 0;
 fail:
  return -1;
}


/**
 * Parse a let-statement
 * 
 * @return  Zero on success, -1 on error, 1 if the caller should go to `redo`
 */
static int parse_let(void)
{
  NEW_NODE(let, LET);
  CHARS(variable);
  TEST_FOR_KEYWORD(":");
  *end = prev_end_char;
  SKIP_SPACES(line);
  if (*line == '{')
#define inner value
    BRANCH(NULL);
#undef inner
  else
    LEAF;
  if (*line == '\0')
    {
      line = original, end = line + strlen(line), prev_end_char = '\0';
      NEW_ERROR(1, ERROR, "too few parameters");
    }
  else if (*line != '{')
    {
#define node subnode
      NEW_NODE(string, STRING);
      NO_JUMP;
      CHARS(string);
      node->loc_end = (size_t)(end - LINE);
#undef node
      node->value = (mds_kbdc_tree_t*)subnode;
      END;
    }
  else
    {
#define node subnode
#define inner elements
      NEW_NODE(array, ARRAY);
      BRANCH("}");
      node->loc_end = node->loc_start + 1;
#undef inner
#undef node
      in_array = 1;
      line++;
      return 1;
    }
  
  return 0;
 fail:
  return -1;
}


/**
 * Parse an end-statement
 * 
 * @return  Zero on success, -1 on error, 1 if the caller should go to `redo`
 */
static int parse_end(void)
{
  if (stack_ptr == 0)
    {
      NEW_ERROR(1, ERROR, "runaway ‘end’ statement");
      return 0;
    }
  line += strlen(line);
  *end = prev_end_char, prev_end_char = '\0';
  SKIP_SPACES(line);
  while (keyword_stack[--stack_ptr] == NULL);
  if (*line == '\0')
    {
      line = original, end = line + strlen(line);
      NEW_ERROR(1, ERROR, "expecting a keyword after ‘end’");
    }
  else if (strcmp(line, keyword_stack[stack_ptr]))
    NEW_ERROR(1, ERROR, "expected ‘%s’ but got ‘%s’", keyword_stack[stack_ptr], line);
  NEXT;
  
  return 0;
 fail:
  return -1;
}


/**
 * Parse a mapping- or value-statement
 * 
 * @return  Zero on success, -1 on error, 1 if the caller should go to `redo`
 */
static int parse_map(void)
{
  size_t stack_orig = stack_ptr + 1;
  char* colon;
#define node supernode
#define inner sequence
  NEW_NODE(map, MAP);
  node->loc_end = node->loc_start;
  BRANCH(":");
#undef inner
#undef node
  SEQUENCE(1);
  SEQUENCE_FULLY_POPPED;
#define node supernode
#define inner result
  stack_ptr--;
  *end = prev_end_char;
  supernode->loc_end = (size_t)(end - LINE);
  SKIP_SPACES(line);
  if (colon = line, *line++ != ':')
    {
      LEAF;
      prev_end_char = *end;
      return 0; /* Not an error in functions, or if \set is access, even indirectly. */
    }
  BRANCH(":");
#undef inner
#undef node
  SEQUENCE(1);
  SEQUENCE_FULLY_POPPED;
  stack_ptr--;
  *end = prev_end_char;
  supernode->loc_end = (size_t)(end - LINE);
  SKIP_SPACES(line);
#define node supernode
  LEAF;
#undef node
  if (supernode->result == NULL)
    {
      NEW_ERROR(1, ERROR, "output missing");
      error->start = (size_t)(colon - LINE);
      error->end = error->start + 1;
    }
  if (*line == '\0')
    return prev_end_char = *end, 0;
  end = line + strlen(line), prev_end_char = *end;
  NEW_ERROR(1, ERROR, "too many parameters");
  
  return 0;
 fail:
  return -1;
}


/**
 * Parse a macro call
 * 
 * @return  Zero on success, -1 on error, 1 if the caller should go to `redo`
 */
static int parse_macro_call(void)
{
  char* old_end = end;
  char old_prev_end_char = prev_end_char;
  size_t stack_orig = stack_ptr + 1;
  *end = prev_end_char;
  end = strchrnul(line, '(');
  prev_end_char = *end, *end = '\0';
  if (prev_end_char)
    {
#define node supernode
#define inner arguments
      NEW_NODE(macro_call, MACRO_CALL);
      old_end = end, old_prev_end_char = prev_end_char;
      NO_JUMP;
      *old_end = '\0';
      CHARS(name);
      BRANCH(NULL);
      end = old_end, prev_end_char = old_prev_end_char;
      line++;
#undef inner
#undef node
      SEQUENCE(0);
      SEQUENCE_FULLY_POPPED;
#define node supernode
      if (*line == ')')
	{
	  line++;
	  SKIP_SPACES(line);
	  if (*line)
	    {
	      NEW_ERROR(1, ERROR, "extra token after macro call");
	      error->end = strlen(LINE);
	    }
	}
      else
	{
	  NEW_ERROR(1, ERROR, "missing ‘)’");
	  error->start = (size_t)(strchr(LINE, '(') - LINE);
	  error->end   = error->start + 1;
	}
      stack_ptr--;
      NEXT;
      return 0;
#undef node
    }
  *old_end = '\0';
  end = old_end;
  prev_end_char = old_prev_end_char;
  if (strchr("}", *line))
    NEW_ERROR(1, ERROR, "runaway ‘%c’", *line);
  else
    NEW_ERROR(1, ERROR, "invalid syntax ‘%s’", line);
  
  return 0;
 fail:
  return -1;
}


/**
 * Parse a line of an array
 * 
 * @return  Zero on success, -1 on error, 1 if the caller should go to `redo`
 */
static int parse_array_elements(void)
{
  for (;;)
    {
      SKIP_SPACES(line);
      if (*line == '\0')
	return 0;
      else if (*line == '}')
	{
	  line++;
	  end = line + strlen(line);
	  END;
	  line = end, prev_end_char = '\0';
	  in_array = 0;
	  stack_ptr -= 2;
	  NEXT;
	  return 0;
	}
      else
	{
	  NEW_NODE(string, STRING);
	  NO_JUMP;
	  CHARS(string);
	  LEAF;
	  node->loc_end = (size_t)(end - LINE);
	  *end = prev_end_char;
	  line = end;
	}
    }
  
 fail:
  return -1;
}


/**
 * Parse a line
 * 
 * @return  Zero on success, -1 on error
 */
static int parse_line(void)
{
#define p(function)				\
  do						\
    {						\
      fail_if (r = function(), r < 0);		\
      if (r > 0)				\
	goto redo;				\
    }						\
  while (0)
  
  int r;
  
 redo:
  if (in_array)  p (parse_array_elements);
  else if (!strcmp(line, "have_chars"))
    MAKE_LEAF(assumption_have_chars, ASSUMPTION_HAVE_CHARS, QUOTES_1(chars));
  else if (!strcmp(line, "have_range"))
    MAKE_LEAF(assumption_have_range, ASSUMPTION_HAVE_RANGE, CHARS(first); CHARS(last); END);
  else if (!strcmp(line, "have"))  MAKE_LEAF(assumption_have, ASSUMPTION_HAVE, KEYS(data); END);
  else if (!strcmp(line, "information"))  MAKE_BRANCH(information, INFORMATION, NO_PARAMETERS("information"));
  else if (!strcmp(line, "assumption"))  MAKE_BRANCH(assumption, ASSUMPTION, NO_PARAMETERS("assumption"));
  else if (!strcmp(line, "return"))  MAKE_LEAF(return, RETURN, NO_PARAMETERS("return"));
  else if (!strcmp(line, "continue"))  MAKE_LEAF(continue, CONTINUE, NO_PARAMETERS("continue"));
  else if (!strcmp(line, "break"))  MAKE_LEAF(break, BREAK, NO_PARAMETERS("break"));
  else if (!strcmp(line, "language"))  MAKE_LEAF(information_language, INFORMATION_LANGUAGE, QUOTES_1(data));
  else if (!strcmp(line, "country"))  MAKE_LEAF(information_country, INFORMATION_COUNTRY, QUOTES_1(data));
  else if (!strcmp(line, "variant"))  MAKE_LEAF(information_variant, INFORMATION_VARIANT, QUOTES_1(data));
  else if (!strcmp(line, "include"))  MAKE_LEAF(include, INCLUDE, QUOTES_1(filename));
  else if (!strcmp(line, "function"))  MAKE_BRANCH(function, FUNCTION, NAMES_1(name));
  else if (!strcmp(line, "macro"))  MAKE_BRANCH(macro, MACRO, NAMES_1(name));
  else if (!strcmp(line, "if"))  MAKE_BRANCH(if, IF, CHARS(condition); END);
  else if (!strcmp(line, "else"))  p (parse_else);
  else if (!strcmp(line, "for"))  p (parse_for);
  else if (!strcmp(line, "let"))  p (parse_let);
  else if (!strcmp(line, "end"))  p (parse_end);
  else if (strchr("\\\"<([0123456789", *line))  p (parse_map);
  else  p (parse_macro_call);
  
  *end = prev_end_char;
  
  return 0;
 fail:
  return -1;
#undef p
}



/***  Parsing root-procedure.  ***/


/**
 * Parse a file into a syntax tree
 * 
 * @param   filename   The filename of the file to parse
 * @param   result_    Output parameter for the parsing result
 * @return             -1 if an error occursed that cannot be stored in `result`, zero otherwise
 */
int parse_to_tree(const char* restrict filename, mds_kbdc_parsed_t* restrict result_)
{
  size_t line_n;
  int r, saved_errno;
  
  
  /* Prepare parsing. */
  result = result_;
  stack_ptr = 0;
  keyword_stack = NULL;
  tree_stack = NULL;
  in_array = 0;
  
  fail_if (xmalloc(result->source_code, 1, mds_kbdc_source_code_t));
  mds_kbdc_source_code_initialise(result->source_code);
  
  r = get_pathname(filename);
  fail_if (r < 0);
  if (r == 0)
    return 0;
  
  fail_if (read_source_code());
  fail_if (allocate_stacks());
  
  
  /* Create a node-slot for the tree root. */
  *tree_stack = &(result->tree);
  
  /* Parse the file. */
  for (line_i = 0, line_n = result->source_code->line_count; line_i < line_n; line_i++)
    {
      line = LINE;
      SKIP_SPACES(line);
      if (end = strchrnul(line, ' '), end == line)
	continue;
      prev_end_char = *end, *end = '\0';
      original = line;
      too_few = 0;
      
      parse_line();
    }
  
  
  /* Check parsing state. */
  fail_if (check_for_premature_end_of_file());
  fail_if (check_whether_file_is_empty());
  
  /* Clean up. */
  free(keyword_stack);
  free(tree_stack);
  return 0;
  
 fail:
  saved_errno = errno;
  free(keyword_stack);
  free(tree_stack);
  return errno = saved_errno, -1;
}



#undef MAKE_BRANCH
#undef MAKE_LEAF
#undef SEQUENCE_FULLY_POPPED
#undef SEQUENCE
#undef PURE_KEYS
#undef KEYS
#undef TEST_FOR_KEYWORD
#undef QUOTES_1
#undef QUOTES
#undef END
#undef CHARS
#undef IS_END
#undef NO_JUMP
#undef NAMES_1
#undef NO_PARAMETERS
#undef SKIP_SPACES
#undef LEAF
#undef BRANCH
#undef NEW_NODE
#undef NEW_ERROR
#undef NEXT
#undef LINE
#undef is_name_char
#undef in_range
#undef PRINT_STACK
#undef DEBUG_PROC