expr.cxx

ecos实时嵌入式操作系统

//{{{  Banner                           

//============================================================================
//
//      expr.cxx
//
//      Implementation of the various CDL expression classes.
//
//============================================================================
//####COPYRIGHTBEGIN####
//                                                                          
// ----------------------------------------------------------------------------
// Copyright (C) 1999, 2000, 2001 Red Hat, Inc.
//
// This file is part of the eCos host tools.
//
// 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 2 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, write to the Free Software Foundation, Inc., 
// 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// ----------------------------------------------------------------------------
//                                                                          
//####COPYRIGHTEND####
//============================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):   bartv
// Contact(s):  bartv
// Date:        1999/02/02
// Version:     0.02
//
//####DESCRIPTIONEND####
//============================================================================

//}}}
//{{{  #include's                       

// ----------------------------------------------------------------------------
#include "cdlconfig.h"

// Get the infrastructure types, assertions, tracing and similar
// facilities.
#include <cyg/infra/cyg_ass.h>
#include <cyg/infra/cyg_trac.h>

// <cdlcore.hxx> defines everything implemented in this module.
// It implicitly supplies <string>, <vector> and <map> because
// the class definitions rely on these headers.
#include <cdlcore.hxx>

//}}}

//{{{  Statics                          

// ----------------------------------------------------------------------------
CYGDBG_DEFINE_MEMLEAK_COUNTER(CdlEvalContext);
CYGDBG_DEFINE_MEMLEAK_COUNTER(CdlExpressionBody);
CYGDBG_DEFINE_MEMLEAK_COUNTER(CdlListExpressionBody);
CYGDBG_DEFINE_MEMLEAK_COUNTER(CdlGoalExpressionBody);

//}}}
//{{{  CdlEvalContext                   

// ----------------------------------------------------------------------------
// A utility class to keep track of the context in which expression
// evaluation is happening.

CdlEvalContext::CdlEvalContext(CdlTransaction transaction_arg, CdlNode node_arg, CdlProperty property_arg,
                               CdlToplevel toplevel_arg)
{
    CYG_REPORT_FUNCNAME("CdlEvalContext::constructor");
    CYG_REPORT_FUNCARG4XV(this, transaction_arg, node_arg, property_arg);

    transaction = transaction_arg;
    
    if ((0 == property_arg) && (0 != transaction)) {
        CdlConflict conflict = transaction->get_conflict();
        if (0 != conflict) {
            property_arg = conflict->get_property();
        }
    }
    property    = property_arg;
    
    if ((0 == node_arg) && (0 != transaction)) {
        CdlConflict conflict = transaction->get_conflict();
        if (0 != conflict) {
            node_arg = conflict->get_node();
        }
    }
    node        = node_arg;
    
    if (0 == toplevel_arg) {
        if (0 != transaction) {
            toplevel_arg = transaction->get_toplevel();
        } else if (0 != node) {
            toplevel_arg = node->get_toplevel();
        }
    }
    toplevel = toplevel_arg;
    
    cdlevalcontext_cookie = CdlEvalContext_Magic;
    CYGDBG_MEMLEAK_CONSTRUCTOR();

    CYG_POSTCONDITION_THISC();
    CYG_REPORT_RETURN();
}

CdlEvalContext::~CdlEvalContext()
{
    CYG_REPORT_FUNCNAME("CdlEvalContext::destructor");
    CYG_PRECONDITION_THISC();

    cdlevalcontext_cookie       = CdlEvalContext_Invalid;
    transaction = 0;
    node        = 0;
    property    = 0;
    toplevel    = 0;
    CYGDBG_MEMLEAK_DESTRUCTOR();
    
    CYG_REPORT_RETURN();
}

// Given a context and a reference inside an expression, obtain the node
// being referenced - if it is loaded.
CdlNode
CdlEvalContext::resolve_reference(CdlExpression expr, int index)
{
    CYG_REPORT_FUNCNAMETYPE("CdlEvalContext::resolve_reference", "result %");
    CYG_REPORT_FUNCARG2XV(expr, index);
    CYG_PRECONDITION_THISC();
    CYG_PRECONDITION_CLASSC(expr);
    CYG_PRECONDITIONC((0 <= index) && (index <= (int)expr->references.size()));

    // This expression may be happening in the context of a particular
    // property. If so then the destination may or may not be
    // resolved, which will have been handled when the containing package
    // was loaded. Alternatively this expression may be evaluated inside
    // some arbitrary Tcl code, in which case references remain unbound
    // and need to be resolved the hard way.
    CdlNode result = 0;
    if (0 != this->property) {
        // There is a property, use the bound/unbound reference.
        result = expr->references[index].get_destination();
    } else {
        // The destination name can be retrieved, but we still need some
        // way of resolving it.
        if (0 != this->toplevel) {
            std::string destination_name = expr->references[index].get_destination_name();
            result = this->toplevel->lookup(destination_name);
        }
    }
    
    CYG_REPORT_RETVAL(result);
    return result;
}

// Ditto, but also check that the result is a valuable.
CdlValuable
CdlEvalContext::resolve_valuable_reference(CdlExpression expr, int index)
{
    CYG_REPORT_FUNCNAMETYPE("CdlEvalContext::resolve_reference", "result %");
    CYG_REPORT_FUNCARG2XV(expr, index);

    CdlValuable result  = 0;
    CdlNode     node = this->resolve_reference(expr, index);
    if (0 != node) {
        result = dynamic_cast<CdlValuable>(node);
    }
    CYG_REPORT_RETVAL(result);
    return result;
}

bool
CdlEvalContext::check_this(cyg_assert_class_zeal zeal) const
{
    if (CdlEvalContext_Magic != cdlevalcontext_cookie) {
        return false;
    }
    CYGDBG_MEMLEAK_CHECKTHIS();
    
    if ((0 != transaction) && !transaction->check_this(zeal)) {
        return false;
    }
    if ((0 != toplevel) && !toplevel->check_this(zeal)) {
        return false;
    }
    if ((0 != node) && !node->check_this(zeal)) {
        return false;
    }
    if ((0 != property) && !property->check_this(zeal)) {
        return false;
    }
    return true;
}

//}}}
//{{{  Expression parsing               

//{{{  Description                      

// ----------------------------------------------------------------------------
// There are a number of different entry points related to expression parsing,
// largely to support list and goal expressions. All of these eventually
// end up calling the function
//    continue_parse(expr, data, index, token, token_end)
//
// The expr argument holds an existing expression object that needs to be
// updated. If token is Invalid then we are at the start of an expression
// (but not necessarily at the start of the string).
//
// The data string holds all of the expression that should be parsed.
// It is formed by concatenating all non-option arguments to the
// appropriate property command, with spaces between them.
//
// index is an input/output variable. On input it indicates where in
// the string parsing should continue. On output it indicates the
// location within the string where the terminating token began.
//
// token is an input/output variable. On input it can have the values
// Invalid or And. The former means that we are parsing a completely
// new expression. The latter is used for goal expressions: it is
// necessary to parse a new expression and then combine it with the
// existing one.
//
// token_end is an output variable. It indicates the location within
// the string where the terminating token ended. This is useful for
// e.g. ranges in a list expression.
//
// A conventional recursive descent parser is used.

//}}}
//{{{  Tokenization                     

// ----------------------------------------------------------------------------
// Tokenization.

//{{{  token enum                       

// A separate token enum is necessary, rather than re-using the CdlExprOp
// enum. Some tokens may correspond to several operators, and some tokens
// such as close-bracket do not correspond directly to an operator at all.
enum token {
    T_Invalid           = -2,

    T_EOD               = -1,
    T_Reference         =  1,   // CYGPKG_HAL
    T_String            =  2,   // "hello"
    T_Integer           =  3,   // 123
    T_Double            =  4,   // 3.1415
    T_Range             =  5,   // to
    T_OpenBracket       =  6,   // (
    T_CloseBracket      =  7,   // )
    T_Minus             =  8,   // -
    T_Plus              =  9,   // +
    T_Times             = 10,   // *
    T_Divide            = 11,   // /
    T_Exclamation       = 12,   // !
    T_Tilde             = 13,   // ~
    T_Questionmark      = 14,   // ?
    T_Remainder         = 15,   // %
    T_LeftShift         = 16,   // <<
    T_RightShift        = 17,   // >>
    T_LessThan          = 18,   // <
    T_LessEqual         = 19,   // <=
    T_GreaterThan       = 20,   // >
    T_GreaterEqual      = 21,   // >=
    T_Equal             = 22,   // ==
    T_NotEqual          = 23,   // !=
    T_BitAnd            = 24,   // &
    T_BitXor            = 25,   // ^
    T_BitOr             = 26,   // |
    T_And               = 27,   // &&
    T_Or                = 28,   // ||
    T_Colon             = 29,   // : (in a conditional)
    T_StringConcat      = 30,   // .
    T_Function          = 31,   // is_substr etc.
    T_Comma             = 32,   // , (inside a function)
    T_Implies           = 33,   // implies
    T_Xor               = 34,   // xor
    T_Eqv               = 35    // eqv
    
};

//}}}
//{{{  Statics                          

// Statics to keep track of the current state.
static std::string      current_data            = "";
static unsigned int     current_index           = 0;
static unsigned int     token_start             = 0;
static int              current_char            = EOF;
static token            current_token           = T_Invalid;
static std::string      current_string          = "";
static std::string      current_reference       = "";
static std::string      current_special         = "";
static cdl_int          current_int             = 0;
static double           current_double          = 0.0;
static CdlValueFormat   current_format          = CdlValueFormat_Default;
static int              current_function_id     = 0;

//}}}
//{{{  Character access                 

// ----------------------------------------------------------------------------
// Individual character access.
// Note that current_index is one character past current_char.

// Return the next character in the string, or EOF
static void
next_char()
{
    if (current_index >= current_data.size()) {
        current_char = EOF;
    } else {
        current_char = current_data[current_index++];
    }
}

// Go back a character. This is useful when parsing
// strings. It is the responsibility of the calling code
// to make sure that we are not at the start of the buffer.
static void
backup_char()
{
    CYG_ASSERTC(((EOF == current_char) && (0 < current_index)) || (1 < current_index));
    if (EOF != current_char) {
        current_index--;
    }
    current_char = current_data[current_index - 1];
}

//}}}
//{{{  get_error_location()             

// ----------------------------------------------------------------------------
// Construct part of a diagnostic message, indicating the
// area in the data where the error occurred. This string
// is of the form {...data} ^char^ {data...}. Ideally
// the ^ markers would be on a subsequent line, eliminating
// the need for braces, but there is insufficient control
// of how the message gets presented to the user.
//
// Care has to be taken with EOD.
static std::string
get_error_location()
{
    CYG_REPORT_FUNCNAME("get_error_location");
    std::string result = "";

    // token_start is probably the best place for centering the error.
    // current_index is past the point where the error has occurred.
    if (token_start > 1) {
        if (token_start > 16) {
            result = "{..." + current_data.substr(token_start - 13, 13) + "} ";
        } else {
            result = "{" + current_data.substr(0, token_start) + "}";
        }
    }

    if (current_char == EOF) {
        result += " <end of data>";
    } else {
        result += " ^" + std::string(1, current_data[token_start]) + "^ ";
    }

    if (token_start < current_data.size()) {
        if ((token_start + 16) < current_data.size()) {
            result += "{" + current_data.substr(token_start + 1, current_data.size() - (token_start+1)) + "}";
        } else {
            result += "{" + current_data.substr(token_start, 13) + "...}";
        }
    }

    CYG_REPORT_RETURN();
    return result;
}

// Export this functionality available to other modules, especially func.cxx and its
// argument checking routines.
std::string