1 /* -*- c++ -*- */
2 /*
3  * Copyright © 2010 Intel Corporation
4  *
5  * Permission is hereby granted, free of charge, to any person obtaining a
6  * copy of this software and associated documentation files (the "Software"),
7  * to deal in the Software without restriction, including without limitation
8  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
9  * and/or sell copies of the Software, and to permit persons to whom the
10  * Software is furnished to do so, subject to the following conditions:
11  *
12  * The above copyright notice and this permission notice (including the next
13  * paragraph) shall be included in all copies or substantial portions of the
14  * Software.
15  *
16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
22  * DEALINGS IN THE SOFTWARE.
23  */
24 
25 #ifndef S_EXPRESSION_H
26 #define S_EXPRESSION_H
27 
28 #include "util/strtod.h"
29 #include "list.h"
30 
31 /* Type-safe downcasting macros (also safe to pass NULL) */
32 #define SX_AS_(t,x) ((x) && ((s_expression*) x)->is_##t()) ? ((s_##t*) (x)) \
33                                                            : NULL
34 #define SX_AS_LIST(x)   SX_AS_(list, x)
35 #define SX_AS_SYMBOL(x) SX_AS_(symbol, x)
36 #define SX_AS_NUMBER(x) SX_AS_(number, x)
37 #define SX_AS_INT(x)    SX_AS_(int, x)
38 
39 /* Pattern matching macros */
40 #define MATCH(list, pat) s_match(list, ARRAY_SIZE(pat), pat, false)
41 #define PARTIAL_MATCH(list, pat) s_match(list, ARRAY_SIZE(pat), pat, true)
42 
43 /* For our purposes, S-Expressions are:
44  * - <int>
45  * - <float>
46  * - symbol
47  * - (expr1 expr2 ... exprN)     where exprN is an S-Expression
48  *
49  * Unlike LISP/Scheme, we do not support (foo . bar) pairs.
50  */
51 class s_expression : public exec_node
52 {
53 public:
54    /**
55     * Read an S-Expression from the given string.
56     * Advances the supplied pointer to just after the expression read.
57     *
58     * Any allocation will be performed with 'ctx' as the ralloc owner.
59     */
60    static s_expression *read_expression(void *ctx, const char *&src);
61 
62    /**
63     * Print out an S-Expression.  Useful for debugging.
64     */
65    virtual void print() = 0;
66 
is_list()67    virtual bool is_list()   const { return false; }
is_symbol()68    virtual bool is_symbol() const { return false; }
is_number()69    virtual bool is_number() const { return false; }
is_int()70    virtual bool is_int()    const { return false; }
71 
72 protected:
s_expression()73    s_expression() { }
74 };
75 
76 /* Atoms */
77 
78 class s_number : public s_expression
79 {
80 public:
is_number()81    bool is_number() const { return true; }
82 
83    virtual float fvalue() = 0;
84 
85 protected:
s_number()86    s_number() { }
87 };
88 
89 class s_int : public s_number
90 {
91 public:
s_int(int x)92    s_int(int x) : val(x) { }
93 
is_int()94    bool is_int() const { return true; }
95 
fvalue()96    float fvalue() { return float(this->val); }
value()97    int value() { return this->val; }
98 
99    void print();
100 
101 private:
102    int val;
103 };
104 
105 class s_float : public s_number
106 {
107 public:
s_float(float x)108    s_float(float x) : val(x) { }
109 
fvalue()110    float fvalue() { return this->val; }
111 
112    void print();
113 
114 private:
115    float val;
116 };
117 
118 class s_symbol : public s_expression
119 {
120 public:
121    s_symbol(const char *, size_t);
122 
is_symbol()123    bool is_symbol() const { return true; }
124 
value()125    const char *value() { return this->str; }
126 
127    void print();
128 
129 private:
130    const char *str;
131 };
132 
133 /* Lists of expressions: (expr1 ... exprN) */
134 class s_list : public s_expression
135 {
136 public:
137    s_list();
138 
is_list()139    virtual bool is_list() const { return true; }
140 
141    void print();
142 
143    exec_list subexpressions;
144 };
145 
146 // ------------------------------------------------------------
147 
148 /**
149  * Part of a pattern to match - essentially a record holding a pointer to the
150  * storage for the component to match, along with the appropriate type.
151  */
152 class s_pattern {
153 public:
s_pattern(s_expression * & s)154    s_pattern(s_expression *&s) : p_expr(&s),   type(EXPR)   { }
s_pattern(s_list * & s)155    s_pattern(s_list       *&s) : p_list(&s),   type(LIST)   { }
s_pattern(s_symbol * & s)156    s_pattern(s_symbol     *&s) : p_symbol(&s), type(SYMBOL) { }
s_pattern(s_number * & s)157    s_pattern(s_number     *&s) : p_number(&s), type(NUMBER) { }
s_pattern(s_int * & s)158    s_pattern(s_int        *&s) : p_int(&s),    type(INT)    { }
s_pattern(const char * str)159    s_pattern(const char *str)  : literal(str), type(STRING) { }
160 
161    bool match(s_expression *expr);
162 
163 private:
164    union {
165       s_expression **p_expr;
166       s_list       **p_list;
167       s_symbol     **p_symbol;
168       s_number     **p_number;
169       s_int        **p_int;
170       const char *literal;
171    };
172    enum { EXPR, LIST, SYMBOL, NUMBER, INT, STRING } type;
173 };
174 
175 bool
176 s_match(s_expression *top, unsigned n, s_pattern *pattern, bool partial);
177 
178 #endif /* S_EXPRESSION_H */
179