/* $Id: code.cc,v 1.10 2004/05/27 00:02:01 nuffer Exp $ */
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <iomanip>
#include <iostream>
#include "substr.h"
#include "globals.h"
#include "dfa.h"
#include "parser.h"

// there must be at least one span in list;  all spans must cover
// same range

void Go::compact()
{
	// arrange so that adjacent spans have different targets
	uint i = 0;
	for(uint j = 1; j < nSpans; ++j)
	{
		if(span[j].to != span[i].to)
		{
			++i; span[i].to = span[j].to;
		}
		span[i].ub = span[j].ub;
	}
	nSpans = i + 1;
}

void Go::unmap(Go *base, State *x)
{
	Span *s = span, *b = base->span, *e = &b[base->nSpans];
	uint lb = 0;
	s->ub = 0;
	s->to = NULL;
	for(; b != e; ++b)
	{
		if(b->to == x)
		{
			if((s->ub - lb) > 1)
			{
				s->ub = b->ub;
			}
		} else {
			if(b->to != s->to)
			{
				if(s->ub)
				{
					lb = s->ub; ++s;
				}
				s->to = b->to;
			}
			s->ub = b->ub;
		}
	}
	s->ub = e[-1].ub; ++s;
	nSpans = s - span;
}

void doGen(Go *g, State *s, uchar *bm, uchar m)
{
	Span *b = g->span, *e = &b[g->nSpans];
	uint lb = 0;
	for(; b < e; ++b)
	{
		if(b->to == s)
		{
			for(; lb < b->ub; ++lb)
			{
				bm[lb] |= m;
			}
		}
		lb = b->ub;
	}
}

void prt(std::ostream& o, Go *g, State *s)
{
	Span *b = g->span, *e = &b[g->nSpans];
	uint lb = 0;
	for(; b < e; ++b)
	{
		if(b->to == s)
		{
			printSpan(o, lb, b->ub);
		}
		lb = b->ub;
	}
}

bool matches(Go *g1, State *s1, Go *g2, State *s2)
{
	Span *b1 = g1->span, *e1 = &b1[g1->nSpans];
	uint lb1 = 0;
	Span *b2 = g2->span, *e2 = &b2[g2->nSpans];
	uint lb2 = 0;
	for(;;)
	{
		for(; b1 < e1 && b1->to != s1; ++b1)
		{
			lb1 = b1->ub;
		}
		for(; b2 < e2 && b2->to != s2; ++b2)
		{
			lb2 = b2->ub;
		}
		if(b1 == e1)
		{
			return b2 == e2;
		}
		if(b2 == e2){
			return false;
		}
		if(lb1 != lb2 || b1->ub != b2->ub)
		{
			return false;
		}
		++b1; ++b2;
	}
}

class BitMap {
public:
	static BitMap	*first;
	Go			*go;
	State		*on;
	BitMap		*next;
	uint		i;
	uchar		m;
	public:
	static BitMap *find(Go*, State*);
	static BitMap *find(State*);
	static void gen(std::ostream&, uint, uint);
	static void stats();
	BitMap(Go*, State*);
};

BitMap *BitMap::first = NULL;

BitMap::BitMap(Go *g, State *x) : go(g), on(x), next(first)
{
	first = this;
}

BitMap *BitMap::find(Go *g, State *x)
{
	for(BitMap *b = first; b; b = b->next)
	{
    	if(matches(b->go, b->on, g, x))
    	{
	    	return b;
	    }
    }
    return new BitMap(g, x);
}

BitMap *BitMap::find(State *x)
{
    for(BitMap *b = first; b; b = b->next)
    {
		if(b->on == x)
		{
	    	return b;
	    }
    }
    return NULL;
}

void BitMap::gen(std::ostream &o, uint lb, uint ub)
{
	BitMap *b = first;
	if(b)
	{
		o << "\tstatic unsigned char yybm[] = {";
		uint n = ub - lb;
		uchar *bm = new uchar[n];
		memset(bm, 0, n);
		for(uint i = 0; b; i += n)
		{
			for(uchar m = 0x80; b && m; b = b->next, m >>= 1)
			{
				b->i = i; b->m = m;
				doGen(b->go, b->on, bm-lb, m);
			}
			for(uint j = 0; j < n; ++j)
			{
				if(j%8 == 0)
				{
					o << "\n\t"; ++oline;
				}
				o << std::setw(3) << (uint) bm[j] << ", ";
			}
		}
		o << "\n\t};\n";
		oline += 2;
	}
}

void BitMap::stats()
{
	uint n = 0;
	for(BitMap *b = first; b; b = b->next)
	{
		prt(std::cerr, b->go, b->on); std::cerr << std::endl;
		++n;
	}
	std::cerr << n << " bitmaps\n";
	first = NULL;
}

void genGoTo(std::ostream &o, State *from, State *to, bool & readCh)
{
	if (readCh && from->label + 1 != to->label)
	{
		o << "\tyych = *YYCURSOR;\n";
		readCh = false;
	}
	o  << "\tgoto yy" << to->label << ";\n";
	++oline;
}

void genIf(std::ostream &o, char *cmp, uint v, bool &readCh)
{
	if (readCh)
	{
		o << "\tif((yych = *YYCURSOR) ";
		readCh = false;
	}
	else
	{
		o << "\tif(yych ";
	}
	o << cmp << " '";
	prtCh(o, v);
	o << "')";
}

void indent(std::ostream &o, uint i)
{
	while(i-- > 0)
	{
		o << "\t";
	}
}

static void need(std::ostream &o, uint n, bool & readCh)
{
	if(n == 1)
	{
		o << "\tif(YYLIMIT == YYCURSOR) YYFILL(1);\n";
		++oline;
	}
	else
	{
		o << "\tif((YYLIMIT - YYCURSOR) < " << n << ") YYFILL(" << n << ");\n";
		++oline;
	}
	o << "\tyych = *YYCURSOR;\n";
	readCh = false;
	++oline;
}

void Match::emit(std::ostream &o, bool &readCh)
{
	if (state->link)
	{
		o << "\t++YYCURSOR;\n";
	}
	else if (!readAhead())
	{
		/* do not read next char if match */
		o << "\t++YYCURSOR;\n";
		readCh = true;
	}
	else
	{
		o << "\tyych = *++YYCURSOR;\n";
		readCh = false;
	}
	++oline;
	if(state->link)
	{
		++oline;
		need(o, state->depth, readCh);
	}
}

void Enter::emit(std::ostream &o, bool &readCh)
{
	if(state->link){
		o << "\t++YYCURSOR;\n";
		o << "yy" << label << ":\n";
		oline += 2;
		need(o, state->depth, readCh);
	} else {
		/* we shouldn't need 'rule-following' protection here */
		o << "\tyych = *++YYCURSOR;\n";
		o << "yy" << label << ":\n";
		oline += 2;
		readCh = false;
	}
}

void Save::emit(std::ostream &o, bool &readCh)
{
	o << "\tyyaccept = " << selector << ";\n";
	++oline;
	if(state->link){
		o << "\tYYMARKER = ++YYCURSOR;\n";
		++oline;
		need(o, state->depth, readCh);
	} else {
		o << "\tyych = *(YYMARKER = ++YYCURSOR);\n";
		++oline;
		readCh = false;
	}
}

Move::Move(State *s) : Action(s) {
    ;
}

void Move::emit(std::ostream &o, bool &readCh){
    ;
}

Accept::Accept(State *x, uint n, uint *s, State **r)
    : Action(x), nRules(n), saves(s), rules(r){
    ;
}

void Accept::emit(std::ostream &o, bool &readCh)
{
	bool first = true;
	for(uint i = 0; i < nRules; ++i)
	if(saves[i] != ~0u)
	{
		if(first)
		{
			first = false;
			o << "\tYYCURSOR = YYMARKER;\n";
			o << "\tswitch(yyaccept){\n";
			oline += 2;
		}
		o << "\tcase " << saves[i] << ":";
		genGoTo(o, state, rules[i], readCh);
	}
	if(!first)
	{
		o << "\t}\n";
		++oline;
	}
}

Rule::Rule(State *s, RuleOp *r) : Action(s), rule(r) {
    ;
}

void Rule::emit(std::ostream &o, bool &readCh)
{
	uint back = rule->ctx->fixedLength();
	if(back != ~0u && back > 0u) {
		o << "\tYYCURSOR -= " << back << ";";
	}
	o << "\n";
	++oline;
	line_source(rule->code->line, o);
	o << rule->code->text;
	// not sure if we need this or not.    oline += std::count(rule->code->text, rule->code->text + ::strlen(rule->code->text), '\n');
	o << "\n";
	++oline;
	o << "#line " << ++oline << " \"" << outputFileName << "\"\n";
	//    o << "\n#line " << rule->code->line
	//      << "\n\t" << rule->code->text << "\n";
}

void doLinear(std::ostream &o, uint i, Span *s, uint n, State *from, State *next, bool &readCh)
{
	for(;;)
	{
		State *bg = s[0].to;
		while(n >= 3 && s[2].to == bg && (s[1].ub - s[0].ub) == 1)
		{
			if(s[1].to == next && n == 3)
			{
				indent(o, i); genIf(o, "!=", s[0].ub, readCh); genGoTo(o, from, bg, readCh);
				indent(o, i); genGoTo(o, from, next, readCh);
				return;
			}
			else
			{
				indent(o, i); genIf(o, "==", s[0].ub, readCh); genGoTo(o, from, s[1].to, readCh);
			}
			n -= 2; s += 2;
		}
		if(n == 1)
		{
//	    	if(bg != next){
				indent(o, i); genGoTo(o, from, s[0].to, readCh);
//	    	}
			return;
		}
		else if(n == 2 && bg == next)
		{
			indent(o, i); genIf(o, ">=", s[0].ub, readCh); genGoTo(o, from, s[1].to, readCh);
			indent(o, i); genGoTo(o, from, next, readCh);
			return;
		}
		else
		{
			indent(o, i); genIf(o, "<=", s[0].ub - 1, readCh); genGoTo(o, from, bg, readCh);
			n -= 1; s += 1;
		}
	}
	indent(o, i); genGoTo(o, from, next, readCh);
}

void Go::genLinear(std::ostream &o, State *from, State *next, bool &readCh)
{
	doLinear(o, 0, span, nSpans, from, next, readCh);
}

void genCases(std::ostream &o, uint lb, Span *s)
{
	if(lb < s->ub)
	{
		for(;;)
		{
			o << "\tcase '"; prtCh(o, lb); o << "':";
			if(++lb == s->ub)
			{
				break;
			}
			o << "\n";
			++oline;
		}
	}
}

void Go::genSwitch(std::ostream &o, State *from, State *next, bool &readCh)
{
	if(nSpans <= 2){
		genLinear(o, from, next, readCh);
	}
	else
	{
		State *def = span[nSpans-1].to;
		Span **sP = new Span*[nSpans-1], **r, **s, **t;
	
		t = &sP[0];
		for(uint i = 0; i < nSpans; ++i)
		{
			if(span[i].to != def)
			{
				*(t++) = &span[i];
			}
		}
	
		if (readCh)
		{
			o << "\tswitch((yych = *YYCURSOR)) {\n";
			readCh =false;
		}
		else
		{
			o << "\tswitch(yych){\n";
		}
		++oline;
		while(t != &sP[0])
		{
			r = s = &sP[0];
			if(*s == &span[0])
			genCases(o, 0, *s);
			else
			genCases(o, (*s)[-1].ub, *s);
			State *to = (*s)->to;
			while(++s < t)
			{
				if((*s)->to == to)
				{
					genCases(o, (*s)[-1].ub, *s);
				}
				else
				{
					*(r++) = *s;
				}
			}
			genGoTo(o, from, to, readCh);
			t = r;
		}
		o << "\tdefault:";
		genGoTo(o, from, def, readCh);
		o << "\t}\n";
		++oline;
	
		delete [] sP;
	}
}

void doBinary(std::ostream &o, uint i, Span *s, uint n, State *from, State *next, bool &readCh)
{
	if(n <= 4)
	{
		doLinear(o, i, s, n, from, next, readCh);
	}
	else
	{
		uint h = n/2;
		indent(o, i); genIf(o, "<=", s[h-1].ub - 1, readCh); o << "{\n";
		++oline;
		doBinary(o, i+1, &s[0], h, from, next, readCh);
		indent(o, i); o << "\t} else {\n";
		++oline;
		doBinary(o, i+1, &s[h], n - h, from, next, readCh);
		indent(o, i); o << "\t}\n";
		++oline;
	}
}

void Go::genBinary(std::ostream &o, State *from, State *next, bool &readCh)
{
	doBinary(o, 0, span, nSpans, from, next, readCh);
}

void Go::genBase(std::ostream &o, State *from, State *next, bool &readCh)
{
	if(nSpans == 0)
	{
		return;
	}
	if(!sFlag)
	{
		genSwitch(o, from, next, readCh);
		return;
	}
	if(nSpans > 8)
	{
		Span *bot = &span[0], *top = &span[nSpans-1];
		uint util;
		if(bot[0].to == top[0].to)
		{
			util = (top[-1].ub - bot[0].ub)/(nSpans - 2);
		}
		else
		{
			if(bot[0].ub > (top[0].ub - top[-1].ub))
			{
				util = (top[0].ub - bot[0].ub)/(nSpans - 1);
			}
			else
			{
				util = top[-1].ub/(nSpans - 1);
			}
		}
		if(util <= 2)
		{
			genSwitch(o, from, next, readCh);
			return;
		}
	}
	if(nSpans > 5)
	{
		genBinary(o, from, next, readCh);
	}
	else
	{
		genLinear(o, from, next, readCh);
	}
}

void Go::genGoto(std::ostream &o, State *from, State *next, bool &readCh)
{
	if(bFlag)
	{
		for(uint i = 0; i < nSpans; ++i)
		{
			State *to = span[i].to;
			if(to && to->isBase)
			{
				BitMap *b = BitMap::find(to);
				if(b && matches(b->go, b->on, this, to))
				{
					Go go;
					go.span = new Span[nSpans];
					go.unmap(this, to);
					o << "\tif(yybm[" << b->i << "+";
					if (readCh)
					{
						o << "(yych = *YYCURSOR)";
					}
					else
					{
						o << "yych";
					}
					o << "] & " << (uint) b->m << ")";
					genGoTo(o, from, to, readCh);
					go.genBase(o, from, next, readCh);
					delete [] go.span;
					return;
				}
			}
		}
	}
	genBase(o, from, next, readCh);
}

void State::emit(std::ostream &o, bool &readCh){
	o << "yy" << label << ":";
/*    o << "\nfprintf(stderr, \"<" << label << ">\");\n";*/
	action->emit(o, readCh);
}

uint merge(Span *x0, State *fg, State *bg)
{
	Span *x = x0, *f = fg->go.span, *b = bg->go.span;
	uint nf = fg->go.nSpans, nb = bg->go.nSpans;
	State *prev = NULL, *to;
	// NB: we assume both spans are for same range
	for(;;)
	{
		if(f->ub == b->ub)
		{
			to = f->to == b->to? bg : f->to;
			if(to == prev){
				--x;
			}
			else
			{
				x->to = prev = to;
			}
			x->ub = f->ub;
			++x; ++f; --nf; ++b; --nb;
			if(nf == 0 && nb == 0)
			{
				return x - x0;
			}
		}
		while(f->ub < b->ub)
		{
			to = f->to == b->to? bg : f->to;
			if(to == prev)
			{
				--x;
			}
			else
			{
				x->to = prev = to;
			}
			x->ub = f->ub;
			++x; ++f; --nf;
		}
		while(b->ub < f->ub)
		{
			to = b->to == f->to? bg : f->to;
			if(to == prev)
			{
				--x;
			}
			else
			{
				x->to = prev = to;
			}
			x->ub = b->ub;
			++x; ++b; --nb;
		}
	}
}

const uint cInfinity = ~0;

class SCC {
public:
	State	**top, **stk;
public:
	SCC(uint);
	~SCC();
	void traverse(State*);
};

SCC::SCC(uint size){
	top = stk = new State*[size];
}

SCC::~SCC(){
	delete [] stk;
}

void SCC::traverse(State *x)
{
	*top = x;
	uint k = ++top - stk;
	x->depth = k;
	for(uint i = 0; i < x->go.nSpans; ++i)
	{
		State *y = x->go.span[i].to;
		if(y)
		{
			if(y->depth == 0)
			{
				traverse(y);
			}
			if(y->depth < x->depth)
			{
				x->depth = y->depth;
			}
		}
	}
	if(x->depth == k)
	{
		do
		{
			(*--top)->depth = cInfinity;
			(*top)->link = x;
		} while(*top != x);
	}
}

uint maxDist(State *s)
{
	uint mm = 0;
	for(uint i = 0; i < s->go.nSpans; ++i)
	{
		State *t = s->go.span[i].to;
		if(t)
		{
			uint m = 1;
			if(!t->link)
			{
				m += maxDist(t);
			}
			if(m > mm)
			{
				mm = m;
			}
		}
	}
	return mm;
}

void calcDepth(State *head)
{
	State *t;
	for(State *s = head; s; s = s->next)
	{
		if(s->link == s){
			for(uint i = 0; i < s->go.nSpans; ++i)
			{
				t = s->go.span[i].to;
				if(t && t->link == s)
				{
					goto inSCC;
				}
			}
			s->link = NULL;
		}else
		{
			inSCC:
			s->depth = maxDist(s);
		}
	}
}
 
void DFA::findSCCs()
{
	SCC scc(nStates);
	State *s;

	for(s = head; s; s = s->next)
	{
		s->depth = 0;
		s->link = NULL;
	}

	for(s = head; s; s = s->next)
	{
		if(!s->depth)
		{
			scc.traverse(s);
		}
	}

	calcDepth(head);
}

void DFA::split(State *s)
{
	State *move = new State;
	(void) new Move(move);
	addState(&s->next, move);
	move->link = s->link;
	move->rule = s->rule;
	move->go = s->go;
	s->rule = NULL;
	s->go.nSpans = 1;
	s->go.span = new Span[1];
	s->go.span[0].ub = ubChar;
	s->go.span[0].to = move;
}

void DFA::emit(std::ostream &o)
{
	static uint label = 0;
	State *s;
	uint i;

	findSCCs();
	head->link = head;
	head->depth = maxDist(head);

	uint nRules = 0;
	for(s = head; s; s = s->next)
	{
		if(s->rule && s->rule->accept >= nRules)
		{
			nRules = s->rule->accept + 1;
		}
	}

	uint nSaves = 0;
	uint *saves = new uint[nRules];
	memset(saves, ~0, (nRules)*sizeof(*saves));

	// mark backtracking points
	for(s = head; s; s = s->next)
	{
		RuleOp *ignore = NULL;
		if(s->rule)
		{
			for(i = 0; i < s->go.nSpans; ++i)
			{
				if(s->go.span[i].to && !s->go.span[i].to->rule){
					delete s->action;
					if(saves[s->rule->accept] == ~0u)
					{
						saves[s->rule->accept] = nSaves++;
					}
					(void) new Save(s, saves[s->rule->accept]);
					continue;
				}
			}
			ignore = s->rule;
		}
	}

	// insert actions
	State **rules = new State*[nRules];
	memset(rules, 0, (nRules)*sizeof(*rules));
	State *accept = NULL;
	for(s = head; s; s = s->next)
	{
		State *ow;
		if(!s->rule)
		{
			ow = accept;
		}
		else
		{
			if(!rules[s->rule->accept])
			{
				State *n = new State;
				(void) new Rule(n, s->rule);
				rules[s->rule->accept] = n;
				addState(&s->next, n);
			}
			ow = rules[s->rule->accept];
		}
		for(i = 0; i < s->go.nSpans; ++i)
		if(!s->go.span[i].to)
		{
			if(!ow)
			{
				ow = accept = new State;
				(void) new Accept(accept, nRules, saves, rules);
				addState(&s->next, accept);
			}
			s->go.span[i].to = ow;
		}
	}

	// split ``base'' states into two parts
	for(s = head; s; s = s->next)
	{
		s->isBase = false;
		if(s->link)
		{
			for(i = 0; i < s->go.nSpans; ++i)
			{
				if(s->go.span[i].to == s){
					s->isBase = true;
					split(s);
					if(bFlag)
					{
						BitMap::find(&s->next->go, s);
					}
					s = s->next;
					break;
				}
			}
		}
	}

	// find ``base'' state, if possible
	Span *span = new Span[ubChar - lbChar];
	for(s = head; s; s = s->next)
	{
		if(!s->link)
		{
			for(i = 0; i < s->go.nSpans; ++i)
			{
				State *to = s->go.span[i].to;
				if(to && to->isBase)
				{
					to = to->go.span[0].to;
					uint nSpans = merge(span, s, to);
					if(nSpans < s->go.nSpans)
					{
						delete [] s->go.span;
						s->go.nSpans = nSpans;
						s->go.span = new Span[nSpans];
						memcpy(s->go.span, span, nSpans*sizeof(Span));
					}
					break;
				}
			}
		}
	}
	delete [] span;

	delete head->action;

	++oline;
	o << "\n#line " << ++oline << " \"" << outputFileName << "\"\n";
	o << "{\n\tYYCTYPE yych;\n\tunsigned int yyaccept;\n";
	oline += 3;


	if(bFlag)
	{
		BitMap::gen(o, lbChar, ubChar);
	}

	o << "\tgoto yy" << label << ";\n";
	++oline;
	(void) new Enter(head, label++);

	for(s = head; s; s = s->next)
	{
		s->label = label++;
	}

	for(s = head; s; s = s->next)
	{
		bool readCh = false;
		s->emit(o, readCh);
		s->go.genGoto(o, s, s->next, readCh);
	}
	o << "}\n";
	++oline;

	BitMap::first = NULL;

	delete [] saves;
	delete [] rules;
}