// Copyright (c) 1999-2006 by Digital Mars
// All Rights Reserved
// written by Walter Bright
// http://www.digitalmars.com
// License for redistribution is by either the Artistic License
// in artistic.txt, or the GNU General Public License in gnu.txt.
// See the included readme.txt for details.

/* Simple macro text processor.
 */

#include <stdio.h>
#include <string.h>
#include <time.h>
#include <ctype.h>
#include <assert.h>

#include "rmem.h"
#include "root.h"

#include "macro.h"

#define isidstart(c) (isalpha(c) || (c) == '_')
#define isidchar(c)  (isalnum(c) || (c) == '_')

unsigned char *memdup(unsigned char *p, size_t len)
{
    return (unsigned char *)memcpy(mem.malloc(len), p, len);
}

Macro::Macro(unsigned char *name, size_t namelen, unsigned char *text, size_t textlen)
{
    next = NULL;

#if 1
    this->name = name;
    this->namelen = namelen;

    this->text = text;
    this->textlen = textlen;
#else
    this->name = name;
    this->namelen = namelen;

    this->text = text;
    this->textlen = textlen;
#endif
    inuse = 0;
}


Macro *Macro::search(unsigned char *name, size_t namelen)
{   Macro *table;

    //printf("Macro::search(%.*s)\n", namelen, name);
    for (table = this; table; table = table->next)
    {
	if (table->namelen == namelen &&
	    memcmp(table->name, name, namelen) == 0)
	{
	    //printf("\tfound %d\n", table->textlen);
	    break;
	}
    }
    return table;
}

Macro *Macro::define(Macro **ptable, unsigned char *name, size_t namelen, unsigned char *text, size_t textlen)
{
    //printf("Macro::define('%.*s' = '%.*s')\n", namelen, name, textlen, text);

    Macro *table;

    //assert(ptable);
    for (table = *ptable; table; table = table->next)
    {
	if (table->namelen == namelen &&
	    memcmp(table->name, name, namelen) == 0)
	{
	    table->text = text;
	    table->textlen = textlen;
	    return table;
	}
    }
    table = new Macro(name, namelen, text, textlen);
    table->next = *ptable;
    *ptable = table;
    return table;
}

/**********************************************************
 * Given buffer p[0..end], extract argument marg[0..marglen].
 * Params:
 *	n	0:	get entire argument
 *		1..9:	get nth argument
 *		-1:	get 2nd through end
 */

unsigned extractArgN(unsigned char *p, unsigned end, unsigned char **pmarg, unsigned *pmarglen, int n)
{
    /* Scan forward for matching right parenthesis.
     * Nest parentheses.
     * Skip over $( and $)
     * Skip over "..." and '...' strings inside HTML tags.
     * Skip over <!-- ... --> comments.
     * Skip over previous macro insertions
     * Set marglen.
     */
    unsigned parens = 1;
    unsigned char instring = 0;
    unsigned incomment = 0;
    unsigned intag = 0;
    unsigned inexp = 0;
    unsigned argn = 0;

    unsigned v = 0;

  Largstart:
#if 1
    // Skip first space, if any, to find the start of the macro argument
    if (v < end && isspace(p[v]))
	v++;
#else
    // Skip past spaces to find the start of the macro argument
    for (; v < end && isspace(p[v]); v++)
	;
#endif
    *pmarg = p + v;

    for (; v < end; v++)
    {   unsigned char c = p[v];

	switch (c)
	{
	    case ',':
		if (!inexp && !instring && !incomment && parens == 1)
		{
		    argn++;
		    if (argn == 1 && n == -1)
		    {	v++;
			goto Largstart;
		    }
		    if (argn == n)
			break;
		    if (argn + 1 == n)
		    {	v++;
			goto Largstart;
		    }
		}
		continue;

	    case '(':
		if (!inexp && !instring && !incomment)
		    parens++;
		continue;

	    case ')':
		if (!inexp && !instring && !incomment && --parens == 0)
		{
		    break;
		}
		continue;

	    case '"':
	    case '\'':
		if (!inexp && !incomment && intag)
		{
		    if (c == instring)
			instring = 0;
		    else if (!instring)
			instring = c;
		}
		continue;

	    case '<':
		if (!inexp && !instring && !incomment)
		{
		    if (v + 6 < end &&
			p[v + 1] == '!' &&
			p[v + 2] == '-' &&
			p[v + 3] == '-')
		    {
			incomment = 1;
			v += 3;
		    }
		    else if (v + 2 < end &&
			isalpha(p[v + 1]))
			intag = 1;
		}
		continue;

	    case '>':
		if (!inexp)
		    intag = 0;
		continue;

	    case '-':
		if (!inexp &&
		    !instring &&
		    incomment &&
		    v + 2 < end &&
		    p[v + 1] == '-' &&
		    p[v + 2] == '>')
		{
		    incomment = 0;
		    v += 2;
		}
		continue;

	    case 0xFF:
		if (v + 1 < end)
		{
		    if (p[v + 1] == '{')
			inexp++;
		    else if (p[v + 1] == '}')
			inexp--;
		}
		continue;

	    default:
		continue;
	}
	break;
    }
    if (argn == 0 && n == -1)
	*pmarg = p + v;
    *pmarglen = p + v - *pmarg;
    //printf("extractArg%d('%.*s') = '%.*s'\n", n, end, p, *pmarglen, *pmarg);
    return v;
}


/*****************************************************
 * Expand macro in place in buf.
 * Only look at the text in buf from start to end.
 */

void Macro::expand(OutBuffer *buf, unsigned start, unsigned *pend,
	unsigned char *arg, unsigned arglen)
{
#if 0
    printf("Macro::expand(buf[%d..%d], arg = '%.*s')\n", start, *pend, arglen, arg);
    printf("Buf is: '%.*s'\n", *pend - start, buf->data + start);
#endif

    static int nest;
    if (nest > 100)		// limit recursive expansion
	return;
    nest++;

    unsigned end = *pend;
    assert(start <= end);
    assert(end <= buf->offset);

    /* First pass - replace $0
     */
    arg = memdup(arg, arglen);
    for (unsigned u = start; u + 1 < end; )
    {
	unsigned char *p = buf->data;	// buf->data is not loop invariant

	/* Look for $0, but not $$0, and replace it with arg.
	 */
	if (p[u] == '$' && (isdigit(p[u + 1]) || p[u + 1] == '+'))
	{
	    if (u > start && p[u - 1] == '$')
	    {   // Don't expand $$0, but replace it with $0
		buf->remove(u - 1, 1);
		end--;
		u += 1;	// now u is one past the closing '1'
		continue;
	    }

	    unsigned char c = p[u + 1];
	    int n = (c == '+') ? -1 : c - '0';

	    unsigned char *marg;
	    unsigned marglen;
	    extractArgN(arg, arglen, &marg, &marglen, n);
	    if (marglen == 0)
	    {	// Just remove macro invocation
		//printf("Replacing '$%c' with '%.*s'\n", p[u + 1], marglen, marg);
		buf->remove(u, 2);
		end -= 2;
	    }
	    else if (c == '+')
	    {
		// Replace '$+' with 'arg'
		//printf("Replacing '$%c' with '%.*s'\n", p[u + 1], marglen, marg);
		buf->remove(u, 2);
		buf->insert(u, marg, marglen);
		end += marglen - 2;

		// Scan replaced text for further expansion
		unsigned mend = u + marglen;
		expand(buf, u, &mend, NULL, 0);
		end += mend - (u + marglen);
		u = mend;
	    }
	    else
	    {
		// Replace '$1' with '\xFF{arg\xFF}'
		//printf("Replacing '$%c' with '\xFF{%.*s\xFF}'\n", p[u + 1], marglen, marg);
		buf->data[u] = 0xFF;
		buf->data[u + 1] = '{';
		buf->insert(u + 2, marg, marglen);
		buf->insert(u + 2 + marglen, "\xFF}", 2);
		end += -2 + 2 + marglen + 2;

		// Scan replaced text for further expansion
		unsigned mend = u + 2 + marglen;
		expand(buf, u + 2, &mend, NULL, 0);
		end += mend - (u + 2 + marglen);
		u = mend;
	    }
	    //printf("u = %d, end = %d\n", u, end);
	    //printf("#%.*s#\n", end, &buf->data[0]);
	    continue;
	}

	u++;
    }

    /* Second pass - replace other macros
     */
    for (unsigned u = start; u + 4 < end; )
    {
	unsigned char *p = buf->data;	// buf->data is not loop invariant

	/* A valid start of macro expansion is $(c, where c is
	 * an id start character, and not $$(c.
	 */
	if (p[u] == '$' && p[u + 1] == '(' && isidstart(p[u + 2]))
	{
	    //printf("\tfound macro start '%c'\n", p[u + 2]);
	    unsigned char *name = p + u + 2;
	    unsigned namelen = 0;

	    unsigned char *marg;
	    unsigned marglen;

	    unsigned v;
	    /* Scan forward to find end of macro name and
	     * beginning of macro argument (marg).
	     */
	    for (v = u + 2; v < end; v++)
	    {	unsigned char c = p[v];

		if (!isidchar(c))
		{   // We've gone past the end of the macro name.
		    namelen = v - (u + 2);
		    break;
		}
	    }

	    v += extractArgN(p + v, end - v, &marg, &marglen, 0);
	    assert(v <= end);

	    if (v < end)
	    {	// v is on the closing ')'
		if (u > start && p[u - 1] == '$')
		{   // Don't expand $$(NAME), but replace it with $(NAME)
		    buf->remove(u - 1, 1);
		    end--;
		    u = v;	// now u is one past the closing ')'
		    continue;
		}

		Macro *m = search(name, namelen);
		if (m)
		{
#if 0
		    if (m->textlen && m->text[0] == ' ')
		    {   m->text++;
			m->textlen--;
		    }
#endif
		    if (m->inuse && marglen == 0)
		    {	// Remove macro invocation
			buf->remove(u, v + 1 - u);
			end -= v + 1 - u;
		    }
		    else if (m->inuse && arglen == marglen && memcmp(arg, marg, arglen) == 0)
		    {	// Recursive expansion; just leave in place

		    }
		    else
		    {
			//printf("\tmacro '%.*s'(%.*s) = '%.*s'\n", m->namelen, m->name, marglen, marg, m->textlen, m->text);
#if 1
			marg = memdup(marg, marglen);
			// Insert replacement text
			buf->spread(v + 1, 2 + m->textlen + 2);
			buf->data[v + 1] = 0xFF;
			buf->data[v + 2] = '{';
			memcpy(buf->data + v + 3, m->text, m->textlen);
			buf->data[v + 3 + m->textlen] = 0xFF;
			buf->data[v + 3 + m->textlen + 1] = '}';

			end += 2 + m->textlen + 2;

			// Scan replaced text for further expansion
			m->inuse++;
			unsigned mend = v + 1 + 2+m->textlen+2;
			expand(buf, v + 1, &mend, marg, marglen);
			end += mend - (v + 1 + 2+m->textlen+2);
			m->inuse--;

			buf->remove(u, v + 1 - u);
			end -= v + 1 - u;
			u += mend - (v + 1);
#else
			// Insert replacement text
			buf->insert(v + 1, m->text, m->textlen);
			end += m->textlen;

			// Scan replaced text for further expansion
			m->inuse++;
			unsigned mend = v + 1 + m->textlen;
			expand(buf, v + 1, &mend, marg, marglen);
			end += mend - (v + 1 + m->textlen);
			m->inuse--;

			buf->remove(u, v + 1 - u);
			end -= v + 1 - u;
			u += mend - (v + 1);
#endif
			mem.free(marg);
			//printf("u = %d, end = %d\n", u, end);
			//printf("#%.*s#\n", end - u, &buf->data[u]);
			continue;
		    }
		}
		else
		{
		    // Replace $(NAME) with nothing
		    buf->remove(u, v + 1 - u);
		    end -= (v + 1 - u);
		    continue;
		}
	    }
	}
	u++;
    }
    mem.free(arg);
    *pend = end;
    nest--;
}