text: /*	$Id: eqn.c,v 1.44 2014/07/06 19:09:00 schwarze Exp $ */
  /*
   * Copyright (c) 2011 Kristaps Dzonsons <kristaps@bsd.lv>
   *
   * Permission to use, copy, modify, and 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.
   */
  #ifdef HAVE_CONFIG_H
  #include "config.h"
  #endif
  
  #include <assert.h>
  #include <limits.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <time.h>
  
  #include "mandoc.h"
  #include "mandoc_aux.h"
  #include "libmandoc.h"
  #include "libroff.h"
  
  #define	EQN_NEST_MAX	 128 /* maximum nesting of defines */
  #define	EQN_MSG(t, x)	 mandoc_msg((t), (x)->parse, (x)->eqn.ln, (x)->eqn.pos, NULL)
  
  enum	eqn_rest {
  	EQN_DESCOPE,
  	EQN_ERR,
  	EQN_OK,
  	EQN_EOF
  };
  
  enum	eqn_symt {
  	EQNSYM_alpha,
  	EQNSYM_beta,
  	EQNSYM_chi,
  	EQNSYM_delta,
  	EQNSYM_epsilon,
  	EQNSYM_eta,
  	EQNSYM_gamma,
  	EQNSYM_iota,
  	EQNSYM_kappa,
  	EQNSYM_lambda,
  	EQNSYM_mu,
  	EQNSYM_nu,
  	EQNSYM_omega,
  	EQNSYM_omicron,
  	EQNSYM_phi,
  	EQNSYM_pi,
  	EQNSYM_ps,
  	EQNSYM_rho,
  	EQNSYM_sigma,
  	EQNSYM_tau,
  	EQNSYM_theta,
  	EQNSYM_upsilon,
  	EQNSYM_xi,
  	EQNSYM_zeta,
  	EQNSYM_DELTA,
  	EQNSYM_GAMMA,
  	EQNSYM_LAMBDA,
  	EQNSYM_OMEGA,
  	EQNSYM_PHI,
  	EQNSYM_PI,
  	EQNSYM_PSI,
  	EQNSYM_SIGMA,
  	EQNSYM_THETA,
  	EQNSYM_UPSILON,
  	EQNSYM_XI,
  	EQNSYM_inter,
  	EQNSYM_union,
  	EQNSYM_prod,
  	EQNSYM_int,
  	EQNSYM_sum,
  	EQNSYM_grad,
  	EQNSYM_del,
  	EQNSYM_times,
  	EQNSYM_cdot,
  	EQNSYM_nothing,
  	EQNSYM_approx,
  	EQNSYM_prime,
  	EQNSYM_half,
  	EQNSYM_partial,
  	EQNSYM_inf,
  	EQNSYM_muchgreat,
  	EQNSYM_muchless,
  	EQNSYM_larrow,
  	EQNSYM_rarrow,
  	EQNSYM_pm,
  	EQNSYM_nequal,
  	EQNSYM_equiv,
  	EQNSYM_lessequal,
  	EQNSYM_moreequal,
  	EQNSYM__MAX
  };
  
  enum	eqnpartt {
  	EQN_DEFINE = 0,
  	EQN_NDEFINE,
  	EQN_TDEFINE,
  	EQN_SET,
  	EQN_UNDEF,
  	EQN_GFONT,
  	EQN_GSIZE,
  	EQN_BACK,
  	EQN_FWD,
  	EQN_UP,
  	EQN_DOWN,
  	EQN__MAX
  };
  
  struct	eqnstr {
  	const char	*name;
  	size_t		 sz;
  };
  
  #define	STRNEQ(p1, sz1, p2, sz2) \
  	((sz1) == (sz2) && 0 == strncmp((p1), (p2), (sz1)))
  #define	EQNSTREQ(x, p, sz) \
  	STRNEQ((x)->name, (x)->sz, (p), (sz))
  
  struct	eqnpart {
  	struct eqnstr	 str;
  	int		(*fp)(struct eqn_node *);
  };
  
  struct	eqnsym {
  	struct eqnstr	 str;
  	const char	*sym;
  };
  
  static	enum eqn_rest	 eqn_box(struct eqn_node *, struct eqn_box *);
  static	struct eqn_box	*eqn_box_alloc(struct eqn_node *,
  				struct eqn_box *);
  static	void		 eqn_box_free(struct eqn_box *);
  static	struct eqn_def	*eqn_def_find(struct eqn_node *,
  				const char *, size_t);
  static	int		 eqn_do_gfont(struct eqn_node *);
  static	int		 eqn_do_gsize(struct eqn_node *);
  static	int		 eqn_do_define(struct eqn_node *);
  static	int		 eqn_do_ign1(struct eqn_node *);
  static	int		 eqn_do_ign2(struct eqn_node *);
  static	int		 eqn_do_tdefine(struct eqn_node *);
  static	int		 eqn_do_undef(struct eqn_node *);
  static	enum eqn_rest	 eqn_eqn(struct eqn_node *, struct eqn_box *);
  static	enum eqn_rest	 eqn_list(struct eqn_node *, struct eqn_box *);
  static	enum eqn_rest	 eqn_matrix(struct eqn_node *, struct eqn_box *);
  static	const char	*eqn_nexttok(struct eqn_node *, size_t *);
  static	const char	*eqn_nextrawtok(struct eqn_node *, size_t *);
  static	const char	*eqn_next(struct eqn_node *,
  				char, size_t *, int);
  static	void		 eqn_rewind(struct eqn_node *);
  
  static	const struct eqnpart eqnparts[EQN__MAX] = {
  	{ { "define", 6 }, eqn_do_define }, /* EQN_DEFINE */
  	{ { "ndefine", 7 }, eqn_do_define }, /* EQN_NDEFINE */
  	{ { "tdefine", 7 }, eqn_do_tdefine }, /* EQN_TDEFINE */
  	{ { "set", 3 }, eqn_do_ign2 }, /* EQN_SET */
  	{ { "undef", 5 }, eqn_do_undef }, /* EQN_UNDEF */
  	{ { "gfont", 5 }, eqn_do_gfont }, /* EQN_GFONT */
  	{ { "gsize", 5 }, eqn_do_gsize }, /* EQN_GSIZE */
  	{ { "back", 4 }, eqn_do_ign1 }, /* EQN_BACK */
  	{ { "fwd", 3 }, eqn_do_ign1 }, /* EQN_FWD */
  	{ { "up", 2 }, eqn_do_ign1 }, /* EQN_UP */
  	{ { "down", 4 }, eqn_do_ign1 }, /* EQN_DOWN */
  };
  
  static	const struct eqnstr eqnmarks[EQNMARK__MAX] = {
  	{ "", 0 }, /* EQNMARK_NONE */
  	{ "dot", 3 }, /* EQNMARK_DOT */
  	{ "dotdot", 6 }, /* EQNMARK_DOTDOT */
  	{ "hat", 3 }, /* EQNMARK_HAT */
  	{ "tilde", 5 }, /* EQNMARK_TILDE */
  	{ "vec", 3 }, /* EQNMARK_VEC */
  	{ "dyad", 4 }, /* EQNMARK_DYAD */
  	{ "bar", 3 }, /* EQNMARK_BAR */
  	{ "under", 5 }, /* EQNMARK_UNDER */
  };
  
  static	const struct eqnstr eqnfonts[EQNFONT__MAX] = {
  	{ "", 0 }, /* EQNFONT_NONE */
  	{ "roman", 5 }, /* EQNFONT_ROMAN */
  	{ "bold", 4 }, /* EQNFONT_BOLD */
  	{ "fat", 3 }, /* EQNFONT_FAT */
  	{ "italic", 6 }, /* EQNFONT_ITALIC */
  };
  
  static	const struct eqnstr eqnposs[EQNPOS__MAX] = {
  	{ "", 0 }, /* EQNPOS_NONE */
  	{ "over", 4 }, /* EQNPOS_OVER */
  	{ "sup", 3 }, /* EQNPOS_SUP */
  	{ "sub", 3 }, /* EQNPOS_SUB */
  	{ "to", 2 }, /* EQNPOS_TO */
  	{ "from", 4 }, /* EQNPOS_FROM */
  };
  
  static	const struct eqnstr eqnpiles[EQNPILE__MAX] = {
  	{ "", 0 }, /* EQNPILE_NONE */
  	{ "pile", 4 }, /* EQNPILE_PILE */
  	{ "cpile", 5 }, /* EQNPILE_CPILE */
  	{ "rpile", 5 }, /* EQNPILE_RPILE */
  	{ "lpile", 5 }, /* EQNPILE_LPILE */
  	{ "col", 3 }, /* EQNPILE_COL */
  	{ "ccol", 4 }, /* EQNPILE_CCOL */
  	{ "rcol", 4 }, /* EQNPILE_RCOL */
  	{ "lcol", 4 }, /* EQNPILE_LCOL */
  };
  
  static	const struct eqnsym eqnsyms[EQNSYM__MAX] = {
  	{ { "alpha", 5 }, "*a" }, /* EQNSYM_alpha */
  	{ { "beta", 4 }, "*b" }, /* EQNSYM_beta */
  	{ { "chi", 3 }, "*x" }, /* EQNSYM_chi */
  	{ { "delta", 5 }, "*d" }, /* EQNSYM_delta */
  	{ { "epsilon", 7 }, "*e" }, /* EQNSYM_epsilon */
  	{ { "eta", 3 }, "*y" }, /* EQNSYM_eta */
  	{ { "gamma", 5 }, "*g" }, /* EQNSYM_gamma */
  	{ { "iota", 4 }, "*i" }, /* EQNSYM_iota */
  	{ { "kappa", 5 }, "*k" }, /* EQNSYM_kappa */
  	{ { "lambda", 6 }, "*l" }, /* EQNSYM_lambda */
  	{ { "mu", 2 }, "*m" }, /* EQNSYM_mu */
  	{ { "nu", 2 }, "*n" }, /* EQNSYM_nu */
  	{ { "omega", 5 }, "*w" }, /* EQNSYM_omega */
  	{ { "omicron", 7 }, "*o" }, /* EQNSYM_omicron */
  	{ { "phi", 3 }, "*f" }, /* EQNSYM_phi */
  	{ { "pi", 2 }, "*p" }, /* EQNSYM_pi */
  	{ { "psi", 2 }, "*q" }, /* EQNSYM_psi */
  	{ { "rho", 3 }, "*r" }, /* EQNSYM_rho */
  	{ { "sigma", 5 }, "*s" }, /* EQNSYM_sigma */
  	{ { "tau", 3 }, "*t" }, /* EQNSYM_tau */
  	{ { "theta", 5 }, "*h" }, /* EQNSYM_theta */
  	{ { "upsilon", 7 }, "*u" }, /* EQNSYM_upsilon */
  	{ { "xi", 2 }, "*c" }, /* EQNSYM_xi */
  	{ { "zeta", 4 }, "*z" }, /* EQNSYM_zeta */
  	{ { "DELTA", 5 }, "*D" }, /* EQNSYM_DELTA */
  	{ { "GAMMA", 5 }, "*G" }, /* EQNSYM_GAMMA */
  	{ { "LAMBDA", 6 }, "*L" }, /* EQNSYM_LAMBDA */
  	{ { "OMEGA", 5 }, "*W" }, /* EQNSYM_OMEGA */
  	{ { "PHI", 3 }, "*F" }, /* EQNSYM_PHI */
  	{ { "PI", 2 }, "*P" }, /* EQNSYM_PI */
  	{ { "PSI", 3 }, "*Q" }, /* EQNSYM_PSI */
  	{ { "SIGMA", 5 }, "*S" }, /* EQNSYM_SIGMA */
  	{ { "THETA", 5 }, "*H" }, /* EQNSYM_THETA */
  	{ { "UPSILON", 7 }, "*U" }, /* EQNSYM_UPSILON */
  	{ { "XI", 2 }, "*C" }, /* EQNSYM_XI */
  	{ { "inter", 5 }, "ca" }, /* EQNSYM_inter */
  	{ { "union", 5 }, "cu" }, /* EQNSYM_union */
  	{ { "prod", 4 }, "product" }, /* EQNSYM_prod */
  	{ { "int", 3 }, "integral" }, /* EQNSYM_int */
  	{ { "sum", 3 }, "sum" }, /* EQNSYM_sum */
  	{ { "grad", 4 }, "gr" }, /* EQNSYM_grad */
  	{ { "del", 3 }, "gr" }, /* EQNSYM_del */
  	{ { "times", 5 }, "mu" }, /* EQNSYM_times */
  	{ { "cdot", 4 }, "pc" }, /* EQNSYM_cdot */
  	{ { "nothing", 7 }, "&" }, /* EQNSYM_nothing */
  	{ { "approx", 6 }, "~~" }, /* EQNSYM_approx */
  	{ { "prime", 5 }, "aq" }, /* EQNSYM_prime */
  	{ { "half", 4 }, "12" }, /* EQNSYM_half */
  	{ { "partial", 7 }, "pd" }, /* EQNSYM_partial */
  	{ { "inf", 3 }, "if" }, /* EQNSYM_inf */
  	{ { ">>", 2 }, ">>" }, /* EQNSYM_muchgreat */
  	{ { "<<", 2 }, "<<" }, /* EQNSYM_muchless */
  	{ { "<-", 2 }, "<-" }, /* EQNSYM_larrow */
  	{ { "->", 2 }, "->" }, /* EQNSYM_rarrow */
  	{ { "+-", 2 }, "+-" }, /* EQNSYM_pm */
  	{ { "!=", 2 }, "!=" }, /* EQNSYM_nequal */
  	{ { "==", 2 }, "==" }, /* EQNSYM_equiv */
  	{ { "<=", 2 }, "<=" }, /* EQNSYM_lessequal */
  	{ { ">=", 2 }, ">=" }, /* EQNSYM_moreequal */
  };
  
  
  enum rofferr
  eqn_read(struct eqn_node **epp, int ln,
  		const char *p, int pos, int *offs)
  {
  	size_t		 sz;
  	struct eqn_node	*ep;
  	enum rofferr	 er;
  
  	ep = *epp;
  
  	/*
  	 * If we're the terminating mark, unset our equation status and
  	 * validate the full equation.
  	 */
  
  	if (0 == strncmp(p, ".EN", 3)) {
  		er = eqn_end(epp);
  		p += 3;
  		while (' ' == *p || '\t' == *p)
  			p++;
  		if ('\0' == *p)
  			return(er);
  		mandoc_vmsg(MANDOCERR_ARG_SKIP, ep->parse,
  		    ln, pos, "EN %s", p);
  		return(er);
  	}
  
  	/*
  	 * Build up the full string, replacing all newlines with regular
  	 * whitespace.
  	 */
  
  	sz = strlen(p + pos) + 1;
  	ep->data = mandoc_realloc(ep->data, ep->sz + sz + 1);
  
  	/* First invocation: nil terminate the string. */
  
  	if (0 == ep->sz)
  		*ep->data = '\0';
  
  	ep->sz += sz;
  	strlcat(ep->data, p + pos, ep->sz + 1);
  	strlcat(ep->data, " ", ep->sz + 1);
  	return(ROFF_IGN);
  }
  
  struct eqn_node *
  eqn_alloc(const char *name, int pos, int line, struct mparse *parse)
  {
  	struct eqn_node	*p;
  	size_t		 sz;
  	const char	*end;
  
  	p = mandoc_calloc(1, sizeof(struct eqn_node));
  
  	if (name && '\0' != *name) {
  		sz = strlen(name);
  		assert(sz);
  		do {
  			sz--;
  			end = name + (int)sz;
  		} while (' ' == *end || '\t' == *end);
  		p->eqn.name = mandoc_strndup(name, sz + 1);
  	}
  
  	p->parse = parse;
  	p->eqn.ln = line;
  	p->eqn.pos = pos;
  	p->gsize = EQN_DEFSIZE;
  
  	return(p);
  }
  
  enum rofferr
  eqn_end(struct eqn_node **epp)
  {
  	struct eqn_node	*ep;
  	struct eqn_box	*root;
  	enum eqn_rest	 c;
  
  	ep = *epp;
  	*epp = NULL;
  
  	ep->eqn.root = mandoc_calloc(1, sizeof(struct eqn_box));
  
  	root = ep->eqn.root;
  	root->type = EQN_ROOT;
  
  	if (0 == ep->sz)
  		return(ROFF_IGN);
  
  	if (EQN_DESCOPE == (c = eqn_eqn(ep, root))) {
  		EQN_MSG(MANDOCERR_EQNNSCOPE, ep);
  		c = EQN_ERR;
  	}
  
  	return(EQN_EOF == c ? ROFF_EQN : ROFF_IGN);
  }
  
  static enum eqn_rest
  eqn_eqn(struct eqn_node *ep, struct eqn_box *last)
  {
  	struct eqn_box	*bp;
  	enum eqn_rest	 c;
  
  	bp = eqn_box_alloc(ep, last);
  	bp->type = EQN_SUBEXPR;
  
  	while (EQN_OK == (c = eqn_box(ep, bp)))
  		/* Spin! */ ;
  
  	return(c);
  }
  
  static enum eqn_rest
  eqn_matrix(struct eqn_node *ep, struct eqn_box *last)
  {
  	struct eqn_box	*bp;
  	const char	*start;
  	size_t		 sz;
  	enum eqn_rest	 c;
  
  	bp = eqn_box_alloc(ep, last);
  	bp->type = EQN_MATRIX;
  
  	if (NULL == (start = eqn_nexttok(ep, &sz))) {
  		EQN_MSG(MANDOCERR_EQNEOF, ep);
  		return(EQN_ERR);
  	}
  	if ( ! STRNEQ(start, sz, "{", 1)) {
  		EQN_MSG(MANDOCERR_EQNSYNT, ep);
  		return(EQN_ERR);
  	}
  
  	while (EQN_OK == (c = eqn_box(ep, bp)))
  		switch (bp->last->pile) {
  		case EQNPILE_LCOL:
  			/* FALLTHROUGH */
  		case EQNPILE_CCOL:
  			/* FALLTHROUGH */
  		case EQNPILE_RCOL:
  			continue;
  		default:
  			EQN_MSG(MANDOCERR_EQNSYNT, ep);
  			return(EQN_ERR);
  		};
  
  	if (EQN_DESCOPE != c) {
  		if (EQN_EOF == c)
  			EQN_MSG(MANDOCERR_EQNEOF, ep);
  		return(EQN_ERR);
  	}
  
  	eqn_rewind(ep);
  	start = eqn_nexttok(ep, &sz);
  	assert(start);
  	if (STRNEQ(start, sz, "}", 1))
  		return(EQN_OK);
  
  	EQN_MSG(MANDOCERR_EQNBADSCOPE, ep);
  	return(EQN_ERR);
  }
  
  static enum eqn_rest
  eqn_list(struct eqn_node *ep, struct eqn_box *last)
  {
  	struct eqn_box	*bp;
  	const char	*start;
  	size_t		 sz;
  	enum eqn_rest	 c;
  
  	bp = eqn_box_alloc(ep, last);
  	bp->type = EQN_LIST;
  
  	if (NULL == (start = eqn_nexttok(ep, &sz))) {
  		EQN_MSG(MANDOCERR_EQNEOF, ep);
  		return(EQN_ERR);
  	}
  	if ( ! STRNEQ(start, sz, "{", 1)) {
  		EQN_MSG(MANDOCERR_EQNSYNT, ep);
  		return(EQN_ERR);
  	}
  
  	while (EQN_DESCOPE == (c = eqn_eqn(ep, bp))) {
  		eqn_rewind(ep);
  		start = eqn_nexttok(ep, &sz);
  		assert(start);
  		if ( ! STRNEQ(start, sz, "above", 5))
  			break;
  	}
  
  	if (EQN_DESCOPE != c) {
  		if (EQN_ERR != c)
  			EQN_MSG(MANDOCERR_EQNSCOPE, ep);
  		return(EQN_ERR);
  	}
  
  	eqn_rewind(ep);
  	start = eqn_nexttok(ep, &sz);
  	assert(start);
  	if (STRNEQ(start, sz, "}", 1))
  		return(EQN_OK);
  
  	EQN_MSG(MANDOCERR_EQNBADSCOPE, ep);
  	return(EQN_ERR);
  }
  
  static enum eqn_rest
  eqn_box(struct eqn_node *ep, struct eqn_box *last)
  {
  	size_t		 sz;
  	const char	*start;
  	char		*left;
  	char		 sym[64];
  	enum eqn_rest	 c;
  	int		 i, size;
  	struct eqn_box	*bp;
  
  	if (NULL == (start = eqn_nexttok(ep, &sz)))
  		return(EQN_EOF);
  
  	if (STRNEQ(start, sz, "}", 1))
  		return(EQN_DESCOPE);
  	else if (STRNEQ(start, sz, "right", 5))
  		return(EQN_DESCOPE);
  	else if (STRNEQ(start, sz, "above", 5))
  		return(EQN_DESCOPE);
  	else if (STRNEQ(start, sz, "mark", 4))
  		return(EQN_OK);
  	else if (STRNEQ(start, sz, "lineup", 6))
  		return(EQN_OK);
  
  	for (i = 0; i < (int)EQN__MAX; i++) {
  		if ( ! EQNSTREQ(&eqnparts[i].str, start, sz))
  			continue;
  		return((*eqnparts[i].fp)(ep) ? EQN_OK : EQN_ERR);
  	}
  
  	if (STRNEQ(start, sz, "{", 1)) {
  		if (EQN_DESCOPE != (c = eqn_eqn(ep, last))) {
  			if (EQN_ERR != c)
  				EQN_MSG(MANDOCERR_EQNSCOPE, ep);
  			return(EQN_ERR);
  		}
  		eqn_rewind(ep);
  		start = eqn_nexttok(ep, &sz);
  		assert(start);
  		if (STRNEQ(start, sz, "}", 1))
  			return(EQN_OK);
  		EQN_MSG(MANDOCERR_EQNBADSCOPE, ep);
  		return(EQN_ERR);
  	}
  
  	for (i = 0; i < (int)EQNPILE__MAX; i++) {
  		if ( ! EQNSTREQ(&eqnpiles[i], start, sz))
  			continue;
  		if (EQN_OK == (c = eqn_list(ep, last)))
  			last->last->pile = (enum eqn_pilet)i;
  		return(c);
  	}
  
  	if (STRNEQ(start, sz, "matrix", 6))
  		return(eqn_matrix(ep, last));
  
  	if (STRNEQ(start, sz, "left", 4)) {
  		if (NULL == (start = eqn_nexttok(ep, &sz))) {
  			EQN_MSG(MANDOCERR_EQNEOF, ep);
  			return(EQN_ERR);
  		}
  		left = mandoc_strndup(start, sz);
  		c = eqn_eqn(ep, last);
  		if (last->last)
  			last->last->left = left;
  		else
  			free(left);
  		if (EQN_DESCOPE != c)
  			return(c);
  		assert(last->last);
  		eqn_rewind(ep);
  		start = eqn_nexttok(ep, &sz);
  		assert(start);
  		if ( ! STRNEQ(start, sz, "right", 5))
  			return(EQN_DESCOPE);
  		if (NULL == (start = eqn_nexttok(ep, &sz))) {
  			EQN_MSG(MANDOCERR_EQNEOF, ep);
  			return(EQN_ERR);
  		}
  		last->last->right = mandoc_strndup(start, sz);
  		return(EQN_OK);
  	}
  
  	for (i = 0; i < (int)EQNPOS__MAX; i++) {
  		if ( ! EQNSTREQ(&eqnposs[i], start, sz))
  			continue;
  		if (NULL == last->last) {
  			EQN_MSG(MANDOCERR_EQNSYNT, ep);
  			return(EQN_ERR);
  		}
  		last->last->pos = (enum eqn_post)i;
  		if (EQN_EOF == (c = eqn_box(ep, last))) {
  			EQN_MSG(MANDOCERR_EQNEOF, ep);
  			return(EQN_ERR);
  		}
  		return(c);
  	}
  
  	for (i = 0; i < (int)EQNMARK__MAX; i++) {
  		if ( ! EQNSTREQ(&eqnmarks[i], start, sz))
  			continue;
  		if (NULL == last->last) {
  			EQN_MSG(MANDOCERR_EQNSYNT, ep);
  			return(EQN_ERR);
  		}
  		last->last->mark = (enum eqn_markt)i;
  		if (EQN_EOF == (c = eqn_box(ep, last))) {
  			EQN_MSG(MANDOCERR_EQNEOF, ep);
  			return(EQN_ERR);
  		}
  		return(c);
  	}
  
  	for (i = 0; i < (int)EQNFONT__MAX; i++) {
  		if ( ! EQNSTREQ(&eqnfonts[i], start, sz))
  			continue;
  		if (EQN_EOF == (c = eqn_box(ep, last))) {
  			EQN_MSG(MANDOCERR_EQNEOF, ep);
  			return(EQN_ERR);
  		} else if (EQN_OK == c)
  			last->last->font = (enum eqn_fontt)i;
  		return(c);
  	}
  
  	if (STRNEQ(start, sz, "size", 4)) {
  		if (NULL == (start = eqn_nexttok(ep, &sz))) {
  			EQN_MSG(MANDOCERR_EQNEOF, ep);
  			return(EQN_ERR);
  		}
  		size = mandoc_strntoi(start, sz, 10);
  		if (EQN_EOF == (c = eqn_box(ep, last))) {
  			EQN_MSG(MANDOCERR_EQNEOF, ep);
  			return(EQN_ERR);
  		} else if (EQN_OK != c)
  			return(c);
  		last->last->size = size;
  	}
  
  	bp = eqn_box_alloc(ep, last);
  	bp->type = EQN_TEXT;
  	for (i = 0; i < (int)EQNSYM__MAX; i++)
  		if (EQNSTREQ(&eqnsyms[i].str, start, sz)) {
  			sym[63] = '\0';
  			(void)snprintf(sym, 62, "\\[%s]", eqnsyms[i].sym);
  			bp->text = mandoc_strdup(sym);
  			return(EQN_OK);
  		}
  
  	bp->text = mandoc_strndup(start, sz);
  	return(EQN_OK);
  }
  
  void
  eqn_free(struct eqn_node *p)
  {
  	int		 i;
  
  	eqn_box_free(p->eqn.root);
  
  	for (i = 0; i < (int)p->defsz; i++) {
  		free(p->defs[i].key);
  		free(p->defs[i].val);
  	}
  
  	free(p->eqn.name);
  	free(p->data);
  	free(p->defs);
  	free(p);
  }
  
  static struct eqn_box *
  eqn_box_alloc(struct eqn_node *ep, struct eqn_box *parent)
  {
  	struct eqn_box	*bp;
  
  	bp = mandoc_calloc(1, sizeof(struct eqn_box));
  	bp->parent = parent;
  	bp->size = ep->gsize;
  
  	if (NULL == parent->first)
  		parent->first = bp;
  	else
  		parent->last->next = bp;
  
  	parent->last = bp;
  	return(bp);
  }
  
  static void
  eqn_box_free(struct eqn_box *bp)
  {
  
  	if (bp->first)
  		eqn_box_free(bp->first);
  	if (bp->next)
  		eqn_box_free(bp->next);
  
  	free(bp->text);
  	free(bp->left);
  	free(bp->right);
  	free(bp);
  }
  
  static const char *
  eqn_nextrawtok(struct eqn_node *ep, size_t *sz)
  {
  
  	return(eqn_next(ep, '"', sz, 0));
  }
  
  static const char *
  eqn_nexttok(struct eqn_node *ep, size_t *sz)
  {
  
  	return(eqn_next(ep, '"', sz, 1));
  }
  
  static void
  eqn_rewind(struct eqn_node *ep)
  {
  
  	ep->cur = ep->rew;
  }
  
  static const char *
  eqn_next(struct eqn_node *ep, char quote, size_t *sz, int repl)
  {
  	char		*start, *next;
  	int		 q, diff, lim;
  	size_t		 ssz, dummy;
  	struct eqn_def	*def;
  
  	if (NULL == sz)
  		sz = &dummy;
  
  	lim = 0;
  	ep->rew = ep->cur;
  again:
  	/* Prevent self-definitions. */
  
  	if (lim >= EQN_NEST_MAX) {
  		EQN_MSG(MANDOCERR_ROFFLOOP, ep);
  		return(NULL);
  	}
  
  	ep->cur = ep->rew;
  	start = &ep->data[(int)ep->cur];
  	q = 0;
  
  	if ('\0' == *start)
  		return(NULL);
  
  	if (quote == *start) {
  		ep->cur++;
  		q = 1;
  	}
  
  	start = &ep->data[(int)ep->cur];
  
  	if ( ! q) {
  		if ('{' == *start || '}' == *start)
  			ssz = 1;
  		else
  			ssz = strcspn(start + 1, " ^~\"{}\t") + 1;
  		next = start + (int)ssz;
  		if ('\0' == *next)
  			next = NULL;
  	} else
  		next = strchr(start, quote);
  
  	if (NULL != next) {
  		*sz = (size_t)(next - start);
  		ep->cur += *sz;
  		if (q)
  			ep->cur++;
  		while (' ' == ep->data[(int)ep->cur] ||
  		    '\t' == ep->data[(int)ep->cur] ||
  		    '^' == ep->data[(int)ep->cur] ||
  		    '~' == ep->data[(int)ep->cur])
  			ep->cur++;
  	} else {
  		if (q)
  			EQN_MSG(MANDOCERR_ARG_QUOTE, ep);
  		next = strchr(start, '\0');
  		*sz = (size_t)(next - start);
  		ep->cur += *sz;
  	}
  
  	/* Quotes aren't expanded for values. */
  
  	if (q || ! repl)
  		return(start);
  
  	if (NULL != (def = eqn_def_find(ep, start, *sz))) {
  		diff = def->valsz - *sz;
  
  		if (def->valsz > *sz) {
  			ep->sz += diff;
  			ep->data = mandoc_realloc(ep->data, ep->sz + 1);
  			ep->data[ep->sz] = '\0';
  			start = &ep->data[(int)ep->rew];
  		}
  
  		diff = def->valsz - *sz;
  		memmove(start + *sz + diff, start + *sz,
  		    (strlen(start) - *sz) + 1);
  		memcpy(start, def->val, def->valsz);
  		goto again;
  	}
  
  	return(start);
  }
  
  static int
  eqn_do_ign1(struct eqn_node *ep)
  {
  
  	if (NULL == eqn_nextrawtok(ep, NULL))
  		EQN_MSG(MANDOCERR_EQNEOF, ep);
  	else
  		return(1);
  
  	return(0);
  }
  
  static int
  eqn_do_ign2(struct eqn_node *ep)
  {
  
  	if (NULL == eqn_nextrawtok(ep, NULL))
  		EQN_MSG(MANDOCERR_EQNEOF, ep);
  	else if (NULL == eqn_nextrawtok(ep, NULL))
  		EQN_MSG(MANDOCERR_EQNEOF, ep);
  	else
  		return(1);
  
  	return(0);
  }
  
  static int
  eqn_do_tdefine(struct eqn_node *ep)
  {
  
  	if (NULL == eqn_nextrawtok(ep, NULL))
  		EQN_MSG(MANDOCERR_EQNEOF, ep);
  	else if (NULL == eqn_next(ep, ep->data[(int)ep->cur], NULL, 0))
  		EQN_MSG(MANDOCERR_EQNEOF, ep);
  	else
  		return(1);
  
  	return(0);
  }
  
  static int
  eqn_do_define(struct eqn_node *ep)
  {
  	const char	*start;
  	size_t		 sz;
  	struct eqn_def	*def;
  	int		 i;
  
  	if (NULL == (start = eqn_nextrawtok(ep, &sz))) {
  		EQN_MSG(MANDOCERR_EQNEOF, ep);
  		return(0);
  	}
  
  	/*
  	 * Search for a key that already exists.
  	 * Create a new key if none is found.
  	 */
  
  	if (NULL == (def = eqn_def_find(ep, start, sz))) {
  		/* Find holes in string array. */
  		for (i = 0; i < (int)ep->defsz; i++)
  			if (0 == ep->defs[i].keysz)
  				break;
  
  		if (i == (int)ep->defsz) {
  			ep->defsz++;
  			ep->defs = mandoc_reallocarray(ep->defs,
  			    ep->defsz, sizeof(struct eqn_def));
  			ep->defs[i].key = ep->defs[i].val = NULL;
  		}
  
  		ep->defs[i].keysz = sz;
  		ep->defs[i].key = mandoc_realloc(
  		    ep->defs[i].key, sz + 1);
  
  		memcpy(ep->defs[i].key, start, sz);
  		ep->defs[i].key[(int)sz] = '\0';
  		def = &ep->defs[i];
  	}
  
  	start = eqn_next(ep, ep->data[(int)ep->cur], &sz, 0);
  
  	if (NULL == start) {
  		EQN_MSG(MANDOCERR_EQNEOF, ep);
  		return(0);
  	}
  
  	def->valsz = sz;
  	def->val = mandoc_realloc(def->val, sz + 1);
  	memcpy(def->val, start, sz);
  	def->val[(int)sz] = '\0';
  	return(1);
  }
  
  static int
  eqn_do_gfont(struct eqn_node *ep)
  {
  
  	if (NULL == eqn_nextrawtok(ep, NULL)) {
  		EQN_MSG(MANDOCERR_EQNEOF, ep);
  		return(0);
  	}
  	return(1);
  }
  
  static int
  eqn_do_gsize(struct eqn_node *ep)
  {
  	const char	*start;
  	size_t		 sz;
  
  	if (NULL == (start = eqn_nextrawtok(ep, &sz))) {
  		EQN_MSG(MANDOCERR_EQNEOF, ep);
  		return(0);
  	}
  	ep->gsize = mandoc_strntoi(start, sz, 10);
  	return(1);
  }
  
  static int
  eqn_do_undef(struct eqn_node *ep)
  {
  	const char	*start;
  	struct eqn_def	*def;
  	size_t		 sz;
  
  	if (NULL == (start = eqn_nextrawtok(ep, &sz))) {
  		EQN_MSG(MANDOCERR_EQNEOF, ep);
  		return(0);
  	} else if (NULL != (def = eqn_def_find(ep, start, sz)))
  		def->keysz = 0;
  
  	return(1);
  }
  
  static struct eqn_def *
  eqn_def_find(struct eqn_node *ep, const char *key, size_t sz)
  {
  	int		 i;
  
  	for (i = 0; i < (int)ep->defsz; i++)
  		if (ep->defs[i].keysz && STRNEQ(ep->defs[i].key,
  		    ep->defs[i].keysz, key, sz))
  			return(&ep->defs[i]);
  
  	return(NULL);
  }
  