Listing 2. lex Processing of Algebraic Statements
1: %
2: /* This routine is the matching flex routine
to the yacc parser that handles vector/scalar
3: operations. Written February, 1994
4: by D. A. Provins
5: $Header: /home/provinsd/LAS/MOTIF_LAS/RCS/flex.main,v 1.8
1994/06/13 01:23:46 provinsd Exp $
6: */
7: #include <stdlib.h>
8: #include "y.tab.h"
9: extern int DeBuG; /* do_arithmetic sets
if "las_debug" valued */
10: int numlines=1;
11: static int ivalue = 0;
12: float value = 0.0;
13: #undef YY_INPUT
14: #define YY_INPUT(b,r,ms) (r=my_yyinput (b,ms))
15: #define min(a,b) (a<b?a:b)
16: %}
17: NEWLINE \\n
18: EQUAL \\=
19: PLUS \\+
20: MINUS \\-
21: DIGIT [0-9]
22: INT {DIGIT}+
23: FLOAT {DIGIT}*"."{DIGIT}*
24: DOUBLE {DIGIT}*"."?{DIGIT}*([eEdD]
({PLUS}|{MINUS})?{DIGIT}{DIGIT}*)?
25: VAR [a-zA-Z][a-zA-Z0-9]*
26: DIVIDE \\/
27: TIMES \\*
28: RAISE \\^
29: LPAREN \\(
30: RPAREN \\)
31: WS [ \\t]
32: %%
33: {NEWLINE} numlines++; return -1;
34: {EQUAL} {if (DeBuG)
35: printf ("Equal sign\\n");
36: return EQUAL; }
38: {VAR} {if (DeBuG)
39: printf ("Variable <%s>\\n", yytext);
40: return VARIABLE; }
42: {VAR}/{EQUAL} {if (DeBuG)
43: printf ("LHS of equation <%s>\\n", yytext);
44: return LHS; }
46: {INT} {if (DeBuG)
47: printf ("Int <%s>\\n", yytext);
48: ivalue= atoi (yytext);
49: value= ivalue;
50: return NUMBER; }
52: {FLOAT} {if (DeBuG)
53: printf ("Float <%s>\\n", yytext);
54: value= atof (yytext);
55: return NUMBER; }
57: {DOUBLE} {if (DeBuG)
58: printf ("Double <%s>\\n", yytext);
59: value= (float) atof (yytext);
60: return NUMBER; }
62: {PLUS} {if (DeBuG)
63: printf ("Sign <%s>\\n", yytext);
64: return PLUS; }
66: {MINUS} {if (DeBuG)
67: printf ("Sign <%s>\\n", yytext);
68: return MINUS; }
70: {TIMES} {if (DeBuG)
71: printf ("Times <%s>\\n", yytext);
72: return TIMES; }
74: {DIVIDE} {if (DeBuG)
75: printf ("Divide <%s>\\n", yytext);
76: return DIVIDE; }
78: {RAISE} {if (DeBuG)
79: printf ("Raise <%s>\\n", yytext);
80: return RAISE; }
82: {LPAREN} {if (DeBuG)
83: printf ("Left paren\\n");
84: return LPAREN; }
86: {RPAREN} {if (DeBuG)
87: printf ("Right paren\\n");
88: return RPAREN; }
90: {WS} /* eat whitespace */
91: %%
92: /********************************************
93: This routine is replaces the Flex
"internal" YY_INPUT macro
94: that it uses to get input
95: *********************************************
96: int
97: my_yyinput (
98: #ifdef _NO_PROTO
99: buf, max_size)
100: char * buf;
101: int max_size;
102: #else
103: char * buf, int max_size)
104: #endif
105: {
106: /* Elsewhere, "my_arithmetic_string"
must be assigned a value. At that time,
107: "current_pointer" should point to the
108: first character in "my_arithmetic_string",
109: and "end_of_string_pointer" should
be set to the trailing NULL
110: */
111: extern char * my_arithmetic_string,
112: * current_pointer,
113: * end_of_string_pointer;
114: int n = min (max_size, end_of_string_pointer\
- current_pointer);
115: if (n > 0) {
116: memcpy (buf, current_pointer, n);
117: current_pointer += n; }
119: return n;
120: }
121: restart_lex ()
122: {
123: *yy_c_buf_p = (YY_CHAR *) 0;
124: yy_init = 1; /* whether to initialize */
125: yy_start = 0; /* start state number */
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