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/* -*- c++ -*- */

/*

 * Copyright © 2010 Intel Corporation

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the "Software"),

 * to deal in the Software without restriction, including without limitation

 * the rights to use, copy, modify, merge, publish, distribute, sublicense,

 * and/or sell copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice (including the next

 * paragraph) shall be included in all copies or substantial portions of the

 * Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

 * DEALINGS IN THE SOFTWARE.

 */

#pragma once

#ifndef S_EXPRESSION_H

#define S_EXPRESSION_H

#include "main/core.h" /* for Elements */

#include "util/strtod.h"

#include "list.h"

/* Type-safe downcasting macros (also safe to pass NULL) */

#define SX_AS_(t,x) ((x) && ((s_expression*) x)->is_##t()) ? ((s_##t*) (x)) \

                                                           : NULL

#define SX_AS_LIST(x)   SX_AS_(list, x)

#define SX_AS_SYMBOL(x) SX_AS_(symbol, x)

#define SX_AS_NUMBER(x) SX_AS_(number, x)

#define SX_AS_INT(x)    SX_AS_(int, x)

/* Pattern matching macros */

#define MATCH(list, pat) s_match(list, ARRAY_SIZE(pat), pat, false)

#define PARTIAL_MATCH(list, pat) s_match(list, ARRAY_SIZE(pat), pat, true)

/* For our purposes, S-Expressions are:

 * - 

 * - 

 * - symbol

 * - (expr1 expr2 ... exprN)     where exprN is an S-Expression

 *

 * Unlike LISP/Scheme, we do not support (foo . bar) pairs.

 */

class s_expression : public exec_node

{

public:

   /**

    * Read an S-Expression from the given string.

    * Advances the supplied pointer to just after the expression read.

    *

    * Any allocation will be performed with 'ctx' as the ralloc owner.

    */

   static s_expression *read_expression(void *ctx, const char *&src);

   /**

    * Print out an S-Expression.  Useful for debugging.

    */

   virtual void print() = 0;

   virtual bool is_list()   const { return false; }

   virtual bool is_symbol() const { return false; }

   virtual bool is_number() const { return false; }

   virtual bool is_int()    const { return false; }

protected:

   s_expression() { }

};

/* Atoms */

class s_number : public s_expression

{

public:

   bool is_number() const { return true; }

   virtual float fvalue() = 0;

protected:

   s_number() { }

};

class s_int : public s_number

{

public:

   s_int(int x) : val(x) { }

   bool is_int() const { return true; }

   float fvalue() { return float(this->val); }

   int value() { return this->val; }

   void print();

private:

   int val;

};

class s_float : public s_number

{

public:

   s_float(float x) : val(x) { }

   float fvalue() { return this->val; }

   void print();

private:

   float val;

};

class s_symbol : public s_expression

{

public:

   s_symbol(const char *, size_t);

   bool is_symbol() const { return true; }

   const char *value() { return this->str; }

   void print();

private:

   const char *str;

};

/* Lists of expressions: (expr1 ... exprN) */

class s_list : public s_expression

{

public:

   s_list();

   virtual bool is_list() const { return true; }

   void print();

   exec_list subexpressions;

};

// ------------------------------------------------------------

/**

 * Part of a pattern to match - essentially a record holding a pointer to the

 * storage for the component to match, along with the appropriate type.

 */

class s_pattern {

public:

   s_pattern(s_expression *&s) : p_expr(&s),   type(EXPR)   { }

   s_pattern(s_list       *&s) : p_list(&s),   type(LIST)   { }

   s_pattern(s_symbol     *&s) : p_symbol(&s), type(SYMBOL) { }

   s_pattern(s_number     *&s) : p_number(&s), type(NUMBER) { }

   s_pattern(s_int        *&s) : p_int(&s),    type(INT)    { }

   s_pattern(const char *str)  : literal(str), type(STRING) { }

   bool match(s_expression *expr);

private:

   union {

      s_expression **p_expr;

      s_list       **p_list;

      s_symbol     **p_symbol;

      s_number     **p_number;

      s_int        **p_int;

      const char *literal;

   };

   enum { EXPR, LIST, SYMBOL, NUMBER, INT, STRING } type;

};

bool

s_match(s_expression *top, unsigned n, s_pattern *pattern, bool partial);

#endif /* S_EXPRESSION_H */