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awk: improve comments and constants, no code changes

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2024-07-10 06:58:51 +02:00
parent 45d471d435
commit 2eea3494f1
1 changed files with 27 additions and 20 deletions
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47
editors/awk.c
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@ -307,13 +307,13 @@ static void debug_parse_print_tc(uint32_t n)
| TC_LENGTH) | TC_LENGTH)
#define TS_CONCAT_R (TS_OPERAND | TS_UOPPRE) #define TS_CONCAT_R (TS_OPERAND | TS_UOPPRE)
#define OF_RES1 0x010000 #define OF_RES1 0x010000 /* evaluate(left_node) */
#define OF_RES2 0x020000 #define OF_RES2 0x020000 /* evaluate(right_node) */
#define OF_STR1 0x040000 #define OF_STR1 0x040000 /* ...and use its string value */
#define OF_STR2 0x080000 #define OF_STR2 0x080000 /* ...and use its string value */
#define OF_NUM1 0x100000 #define OF_NUM1 0x100000 /* ...and use its numeric value */
#define OF_CHECKED 0x200000 #define OF_REQUIRED 0x200000 /* left_node must not be NULL */
#define OF_REQUIRED 0x400000 #define OF_CHECKED 0x400000 /* range pattern flip-flop bit */
/* combined operator flags */ /* combined operator flags */
#define xx 0 #define xx 0
@ -331,17 +331,18 @@ static void debug_parse_print_tc(uint32_t n)
#define OPCLSMASK 0xFF00 #define OPCLSMASK 0xFF00
#define OPNMASK 0x007F #define OPNMASK 0x007F
/* operator priority is a highest byte (even: r->l, odd: l->r grouping) /* operator precedence is the highest byte (even: r->l, odd: l->r grouping)
* (for builtins it has different meaning) * (for builtins the byte has a different meaning)
*/ */
#undef P #undef P
#undef PRIMASK #undef PRIMASK
#undef PRIMASK2 #undef PRIMASK2
#define PRIMASK 0x7F000000
#define PRIMASK2 0x7E000000
/* Smaller 'x' means _higher_ operator precedence */ /* Smaller 'x' means _higher_ operator precedence */
#define PRECEDENCE(x) (x << 24) #define PRECEDENCE(x) (x << 24)
#define P(x) PRECEDENCE(x) #define P(x) PRECEDENCE(x)
#define PRIMASK 0x7F000000 #define LOWEST_PRECEDENCE PRIMASK
#define PRIMASK2 0x7E000000
/* Operation classes */ /* Operation classes */
#define SHIFT_TIL_THIS 0x0600 #define SHIFT_TIL_THIS 0x0600
@ -1424,7 +1425,7 @@ static node *parse_expr(uint32_t term_tc)
debug_parse_print_tc(term_tc); debug_parse_print_tc(term_tc);
debug_printf_parse("\n"); debug_printf_parse("\n");
sn.info = PRIMASK; sn.info = LOWEST_PRECEDENCE;
sn.r.n = sn.a.n = getline_node = NULL; sn.r.n = sn.a.n = getline_node = NULL;
expected_tc = TS_OPERAND | TS_UOPPRE | TC_REGEXP | term_tc; expected_tc = TS_OPERAND | TS_UOPPRE | TC_REGEXP | term_tc;
@ -1443,7 +1444,7 @@ static node *parse_expr(uint32_t term_tc)
if (tc & (TS_BINOP | TC_UOPPOST)) { if (tc & (TS_BINOP | TC_UOPPOST)) {
debug_printf_parse("%s: TS_BINOP | TC_UOPPOST tc:%x\n", __func__, tc); debug_printf_parse("%s: TS_BINOP | TC_UOPPOST tc:%x\n", __func__, tc);
/* for binary and postfix-unary operators, jump back over /* for binary and postfix-unary operators, jump back over
* previous operators with higher priority */ * previous operators with higher precedence */
vn = cn; vn = cn;
while (((t_info & PRIMASK) > (vn->a.n->info & PRIMASK2)) while (((t_info & PRIMASK) > (vn->a.n->info & PRIMASK2))
|| (t_info == vn->info && t_info == TI_COLON) || (t_info == vn->info && t_info == TI_COLON)
@ -1451,7 +1452,7 @@ static node *parse_expr(uint32_t term_tc)
vn = vn->a.n; vn = vn->a.n;
if (!vn->a.n) syntax_error(EMSG_UNEXP_TOKEN); if (!vn->a.n) syntax_error(EMSG_UNEXP_TOKEN);
} }
if (t_info == TI_TERNARY) /* "?" operator */ if (t_info == TI_TERNARY) /* "?" token */
//TODO: why? //TODO: why?
t_info += PRECEDENCE(6); t_info += PRECEDENCE(6);
cn = vn->a.n->r.n = new_node(t_info); cn = vn->a.n->r.n = new_node(t_info);
@ -1483,11 +1484,10 @@ static node *parse_expr(uint32_t term_tc)
} }
expected_tc = TS_OPERAND | TS_UOPPRE | TC_REGEXP; expected_tc = TS_OPERAND | TS_UOPPRE | TC_REGEXP;
if (t_info == TI_PGETLINE) { if (t_info == TI_PGETLINE) { /* "|" token */
/* it's a pipe token "|" */ next_token(TC_GETLINE); /* must be folowed by "getline" */
next_token(TC_GETLINE); /* give maximum precedence to this pipe */
/* give maximum priority to this pipe */ cn->info &= ~PRIMASK; /* sets PRECEDENCE(0) */
cn->info &= ~PRIMASK;
expected_tc = TS_OPERAND | TS_UOPPRE | TS_BINOP | term_tc; expected_tc = TS_OPERAND | TS_UOPPRE | TS_BINOP | term_tc;
} }
} else { } else {
@ -1498,7 +1498,7 @@ static node *parse_expr(uint32_t term_tc)
vn->a.n = cn; vn->a.n = cn;
continue; continue;
} }
/* It wasn't a binary or unary_postfix operator */ /* It wasn't a binary or postfix-unary operator */
debug_printf_parse("%s: other, t_info:%x\n", __func__, t_info); debug_printf_parse("%s: other, t_info:%x\n", __func__, t_info);
/* for operands and prefix-unary operators, attach them /* for operands and prefix-unary operators, attach them
@ -1572,6 +1572,13 @@ static node *parse_expr(uint32_t term_tc)
break; break;
case TC_GETLINE: case TC_GETLINE:
/* "getline" is a function, not a statement.
* Works in gawk:
* r = ["SHELL CMD" | ] getline [VAR] [<"FILE"]
* if (getline <"FILE" < 0) print "Can't read FILE"
* while ("SHELL CMD" | getline > 0) ...
* Returns: 1 successful read, 0 EOF, -1 error (sets ERRNO)
*/
debug_printf_parse("%s: TC_GETLINE\n", __func__); debug_printf_parse("%s: TC_GETLINE\n", __func__);
getline_node = cn; getline_node = cn;
expected_tc = TS_OPERAND | TS_UOPPRE | TS_BINOP | term_tc; expected_tc = TS_OPERAND | TS_UOPPRE | TS_BINOP | term_tc;