scc

Simple C99 Compiler
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commit 3134fea3e8d461d77eb23d8f91291e985f28d4ba
parent 5e5442e6bf058c1f8b7b9674ae008670cdadeae2
Author: Roberto E. Vargas Caballero <k0ga@shike2.com>
Date:   Thu, 27 Mar 2014 21:13:37 +0100

Refactorize operator function in lex.c

This new version is more readable and clear than previous

Diffstat:
lex.c | 78++++++++++++++++++++++++++++++++----------------------------------------------
1 file changed, 32 insertions(+), 46 deletions(-)

diff --git a/lex.c b/lex.c @@ -165,48 +165,17 @@ iden(void) } static uint8_t -follow(uint8_t op, uint8_t eq, uint8_t rep) +follow(int expect, int ifyes, int ifno) { register int c = getc(yyin); - yybuf[1] = c; - yybuf[2] = '\0'; - if (c == '=') - return eq; - else if (c == op && rep) - return rep; - - yybuf[1] = '\0'; - ungetc(c, yyin); - return op; -} - -static uint8_t -rel_shift(uint8_t op) -{ - static uint8_t tokens[2][3] = { - {GE, SHL, SHL_EQ}, - {LE, SHR, SHR_EQ} - }; - register int c = getc(yyin); - register char *tp = tokens[op == '>']; - - yybuf[1] = c; - yybuf[2] = '\0'; - if (c == '=') { - return tp[0]; - } else if (c == op) { - if ((c = getc(yyin)) == '=') { - yybuf[2] = c; - yybuf[3] = '\0'; - return tp[2]; - } - op = tp[1]; - } else { - yybuf[1] = '\0'; + if (c == expect) { + yybuf[1] = c; + yybuf[2] = 0; + return ifyes; } ungetc(c, yyin); - return op; + return ifno; } static uint8_t @@ -227,6 +196,23 @@ minus(void) } static uint8_t +relational(uint8_t op, uint8_t equal, uint8_t shift, uint8_t assig) +{ + register int c = getc(yyin); + + yybuf[1] = c; + yybuf[2] = '\0'; + + if (c == '=') + return equal; + if (c == op) + return follow('=', assig, shift); + ungetc(c, yyin); + yybuf[1] = '\0'; + return op; +} + +static uint8_t operator(void) { register uint8_t c = getc(yyin); @@ -234,15 +220,15 @@ operator(void) yybuf[0] = c; yybuf[1] = '\0'; switch (c) { - case '=': return follow('=', EQ, 0); - case '^': return follow('^', XOR_EQ, 0); - case '*': return follow('*', MUL_EQ, 0); - case '!': return follow('!', NE, 0); - case '+': return follow('+', ADD_EQ, INC); - case '&': return follow('&', AND_EQ, AND); - case '|': return follow('|', OR_EQ, OR); - case '<': return rel_shift('<'); - case '>': return rel_shift('>'); + case '<': return relational('<', LE, SHL, SHL_EQ); + case '>': return relational('>', GE, SHR, SHR_EQ); + case '+': return follow('+', INC, follow('=', ADD_EQ, '+')); + case '=': return follow('=', EQ, '='); + case '^': return follow('=', XOR_EQ, '^'); + case '*': return follow('=', MUL_EQ, '*'); + case '!': return follow('=', NE, '!'); + case '&': return follow('=', AND_EQ, AND); + case '|': return follow('=', OR_EQ, OR); case '-': return minus(); default: return c; }