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      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 #pragma once
     26 #ifndef S_EXPRESSION_H
     27 #define S_EXPRESSION_H
     28 
     29 #include "strtod.h"
     30 #include "list.h"
     31 
     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 /* For our purposes, S-Expressions are:
     40  * - <int>
     41  * - <float>
     42  * - symbol
     43  * - (expr1 expr2 ... exprN)     where exprN is an S-Expression
     44  *
     45  * Unlike LISP/Scheme, we do not support (foo . bar) pairs.
     46  */
     47 class s_expression : public exec_node
     48 {
     49 public:
     50    /**
     51     * Read an S-Expression from the given string.
     52     * Advances the supplied pointer to just after the expression read.
     53     *
     54     * Any allocation will be performed with 'ctx' as the hieralloc owner.
     55     */
     56    static s_expression *read_expression(void *ctx, const char *&src);
     57 
     58    /**
     59     * Print out an S-Expression.  Useful for debugging.
     60     */
     61    virtual void print() = 0;
     62 
     63    virtual bool is_list()   const { return false; }
     64    virtual bool is_symbol() const { return false; }
     65    virtual bool is_number() const { return false; }
     66    virtual bool is_int()    const { return false; }
     67 
     68 protected:
     69    s_expression() { }
     70    virtual ~s_expression() { } // GCC error about accessible nonvirtual dctor
     71 };
     72 
     73 /* Atoms */
     74 
     75 class s_number : public s_expression
     76 {
     77 public:
     78    bool is_number() const { return true; }
     79 
     80    virtual float fvalue() = 0;
     81 
     82 protected:
     83    s_number() { }
     84 };
     85 
     86 class s_int : public s_number
     87 {
     88 public:
     89    s_int(int x) : val(x) { }
     90 
     91    bool is_int() const { return true; }
     92 
     93    float fvalue() { return float(this->val); }
     94    int value() { return this->val; }
     95 
     96    void print();
     97 
     98 private:
     99    int val;
    100 };
    101 
    102 class s_float : public s_number
    103 {
    104 public:
    105    s_float(float x) : val(x) { }
    106 
    107    float fvalue() { return this->val; }
    108 
    109    void print();
    110 
    111 private:
    112    float val;
    113 };
    114 
    115 class s_symbol : public s_expression
    116 {
    117 public:
    118    s_symbol(const char *, size_t);
    119 
    120    bool is_symbol() const { return true; }
    121 
    122    const char *value() { return this->str; }
    123 
    124    void print();
    125 
    126 private:
    127    char *str;
    128 };
    129 
    130 /* Lists of expressions: (expr1 ... exprN) */
    131 class s_list : public s_expression
    132 {
    133 public:
    134    s_list();
    135 
    136    virtual bool is_list() const { return true; }
    137    unsigned length() const;
    138 
    139    void print();
    140 
    141    exec_list subexpressions;
    142 };
    143 
    144 #endif /* S_EXPRESSION_H */
    145