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scaner.c
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scaner.c
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// lexikalni analyzator
#include <stdio.h>
#include <ctype.h>
#include "str.h"
#include "scaner.h"
// promenna pro ulozeni vstupniho souboru
FILE *source;
void setSourceFile(FILE *f)
{
source = f;
}
// ---------------------------------------------------
// HLAVNI TELO LEXIKALNIHO ANALYZATORU
// ---------------------------------------------------
int getNextToken(string *attr)
{
int state = 0;
int c;
// vymazeme obsah atributu a v pripade identifikatoru
// budeme postupne do nej vkladat jeho nazev
strClear(attr);
while (1)
{
// nacteni dalsiho znaku
c = getc(source);
switch (state)
{
case 0:
// zakladni stav automatu
if (isspace(c))
// bila mista - ignorovat
state = 0;
else
if (c == '<')
// komentar
state = 1;
else
if (isalpha(c))
// identifikator nebo klicove slovo
{
strAddChar(attr, c);
state = 2;
}
else
if (c == '+')
// operator ++
state = 3;
else
if (c == '-')
// operator --
state = 4;
else
if (c == '{') return LEFT_VINCULUM;
else
if (c == '}') return RIGHT_VINCULUM;
else
if (c == ';') return SEMICOLON;
else
if (c == EOF) return END_OF_FILE;
else
return LEX_ERROR;
break;
case 1:
// komentar
if (c == '>') state = 0;
else
// komentar pokracuje libovolnymi znaky, zustan ve stavu 1,
// ale kontroluj, zda neprijde EOF (neukonceny komentar)
if (c == EOF) return LEX_ERROR;
break;
case 2:
// identifikator nebo klicove slovo
if (isalnum(c))
// identifikator pokracuje
strAddChar(attr, c);
else
// konec identifikatoru
{
ungetc(c, source); // POZOR! Je potreba vratit posledni nacteny znak
// kontrola, zda se nejedna o klicove slovo
if (strCmpConstStr(attr, "setzero") == 0) return SETZERO;
else
if (strCmpConstStr(attr, "read") == 0) return READ;
else
if (strCmpConstStr(attr, "write") == 0) return WRITE;
else
if (strCmpConstStr(attr, "while") == 0) return WHILE;
else
// jednalo se skutecne o identifikator
return ID;
}
break;
case 3:
// pokracovani operatoru ++
if (c == '+') return INC;
else
return LEX_ERROR;
break;
case 4:
// pokracovani operatoru --
if (c == '-') return DEC;
else
return LEX_ERROR;
break;
}
}
}