1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
|
/* Parser and scanner for calc in D. -*- D -*-
Copyright (C) 2018-2021 Free Software Foundation, Inc.
This file is part of Bison, the GNU Compiler Compiler.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
%language "D"
%define api.parser.class {Calc}
%define parse.error detailed
%define parse.trace
%locations
%union {
int ival;
}
/* Bison Declarations */
%token PLUS "+"
MINUS "-"
STAR "*"
SLASH "/"
LPAR "("
RPAR ")"
EOL "end of line"
%token <ival> NUM "number"
%type <ival> exp
%printer { yyo.write($$); } <ival>
%left "-" "+"
%left "*" "/"
%precedence UNARY /* unary operators */
/* Grammar follows */
%%
input:
line
| input line
;
line:
EOL
| exp EOL { writeln ($exp); }
| error EOL { yyerrok(); }
;
exp:
NUM { $$ = $1; }
| exp "+" exp { $$ = $1 + $3; }
| exp "-" exp { $$ = $1 - $3; }
| exp "*" exp { $$ = $1 * $3; }
| exp "/" exp { $$ = $1 / $3; }
| "+" exp %prec UNARY { $$ = $2; }
| "-" exp %prec UNARY { $$ = -$2; }
| "(" exp ")" { $$ = $2; }
;
%%
import std.range.primitives;
import std.stdio;
auto calcLexer(R)(R range)
if (isInputRange!R && is(ElementType!R : dchar))
{
return new CalcLexer!R(range);
}
auto calcLexer(File f)
{
import std.algorithm : map, joiner;
import std.utf : byDchar;
return f.byChunk(1024) // avoid making a syscall roundtrip per char
.map!(chunk => cast(char[]) chunk) // because byChunk returns ubyte[]
.joiner // combine chunks into a single virtual range of char
.calcLexer; // forward to other overload
}
class CalcLexer(R) : Lexer
if (isInputRange!R && is(ElementType!R : dchar))
{
R input;
this(R r) { input = r; }
Location location;
// Should be a local in main, shared with %parse-param.
int exit_status = 0;
void yyerror(const Location loc, string s)
{
exit_status = 1;
stderr.writeln(loc.toString(), ": ", s);
}
Symbol yylex()
{
import std.uni : isWhite, isNumber;
// Skip initial spaces
while (!input.empty && input.front != '\n' && isWhite(input.front))
{
location.end.column++;
input.popFront;
}
location.step();
if (input.empty)
return Symbol(TokenKind.YYEOF, location);
// Numbers.
if (input.front.isNumber)
{
import std.compiler : version_minor;
static if (version_minor >= 95)
{
// from Dlang v2.095.0 onwards std.conv.parse reports
// the number of consumed characters
import std.typecons : Flag, Yes;
import std.conv : parse;
auto parsed = parse!(int, R, Yes.doCount)(input);
int ival = parsed.data;
location.end.column += cast(int) parsed.count;
}
else
{
auto copy = input;
import std.conv : parse;
int ival = input.parse!int;
while (!input.empty && copy.front != input.front)
{
location.end.column++;
copy.popFront;
}
}
return Symbol(TokenKind.NUM, ival, location);
}
// Individual characters
auto ch = input.front;
input.popFront;
location.end.column++;
switch (ch)
{
case '+': return Symbol(TokenKind.PLUS, location);
case '-': return Symbol(TokenKind.MINUS, location);
case '*': return Symbol(TokenKind.STAR, location);
case '/': return Symbol(TokenKind.SLASH, location);
case '(': return Symbol(TokenKind.LPAR, location);
case ')': return Symbol(TokenKind.RPAR, location);
case '\n':
{
location.end.line++;
location.end.column = 1;
return Symbol(TokenKind.EOL, location);
}
default: assert(0);
}
}
}
int main()
{
auto l = calcLexer(stdin);
auto p = new Calc(l);
import core.stdc.stdlib : getenv;
if (getenv("YYDEBUG"))
p.setDebugLevel(1);
p.parse();
return l.exit_status;
}
|
