ConstraintEvaluator.cc

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00001 // -*- mode: c++; c-basic-offset:4 -*-
00002 
00003 // This file is part of libdap, A C++ implementation of the OPeNDAP Data
00004 // Access Protocol.
00005 
00006 // Copyright (c) 2002,2003 OPeNDAP, Inc.
00007 // Author: James Gallagher <jgallagher@opendap.org>
00008 //
00009 // This library is free software; you can redistribute it and/or
00010 // modify it under the terms of the GNU Lesser General Public
00011 // License as published by the Free Software Foundation; either
00012 // version 2.1 of the License, or (at your option) any later version.
00013 //
00014 // This library is distributed in the hope that it will be useful,
00015 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00016 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00017 // Lesser General Public License for more details.
00018 //
00019 // You should have received a copy of the GNU Lesser General Public
00020 // License along with this library; if not, write to the Free Software
00021 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
00022 //
00023 // You can contact OPeNDAP, Inc. at PO Box 112, Saunderstown, RI. 02874-0112.
00024 
00025 #include "config.h"
00026 
00027 static char rcsid[] not_used =
00028     {"$Id: ConstraintEvaluator.cc 19914 2008-11-25 17:26:22Z jimg $"
00029     };
00030 
00031 #include "ConstraintEvaluator.h"
00032 
00033 #include "ce_functions.h"
00034 #include "parser.h"
00035 #include "ce_parser.h"
00036 #include "debug.h"
00037 
00038 struct yy_buffer_state;
00039 yy_buffer_state *ce_expr_scan_string(const char *str);
00040 int ce_exprparse(void *arg);
00041 
00042 // Glue routines declared in expr.lex
00043 void ce_expr_switch_to_buffer(void *new_buffer);
00044 void ce_expr_delete_buffer(void * buffer);
00045 void *ce_expr_string(const char *yy_str);
00046 
00047 namespace libdap {
00048 
00049 ConstraintEvaluator::ConstraintEvaluator()
00050 {
00051     register_functions(*this);
00052 }
00053 
00054 ConstraintEvaluator::~ConstraintEvaluator()
00055 {
00056     // delete all the constants created by the parser for CE evaluation
00057     for (Constants_iter j = constants.begin(); j != constants.end(); j++) {
00058         BaseType *btp = *j ;
00059         delete btp ; btp = 0;
00060     }
00061 
00062     for (Clause_iter k = expr.begin(); k != expr.end(); k++) {
00063         Clause *cp = *k ;
00064         delete cp ; cp = 0;
00065     }
00066 }
00067 
00069 ConstraintEvaluator::Clause_iter
00070 ConstraintEvaluator::clause_begin()
00071 {
00072     return expr.begin() ;
00073 }
00074 
00077 ConstraintEvaluator::Clause_iter
00078 ConstraintEvaluator::clause_end()
00079 {
00080     return expr.end() ;
00081 }
00082 
00085 bool
00086 ConstraintEvaluator::clause_value(Clause_iter &iter, DDS &dds/*, const string &***/)
00087 {
00088     if (expr.empty())
00089         throw InternalErr(__FILE__, __LINE__,
00090                           "There are no CE clauses for *this* DDS object.");
00091 
00092     return (*iter)->value(dds);
00093 }
00094 
00107 void
00108 ConstraintEvaluator::append_clause(int op, rvalue *arg1, rvalue_list *arg2)
00109 {
00110     Clause *clause = new Clause(op, arg1, arg2);
00111 
00112     expr.push_back(clause);
00113 }
00114 
00124 void
00125 ConstraintEvaluator::append_clause(bool_func func, rvalue_list *args)
00126 {
00127     Clause *clause = new Clause(func, args);
00128 
00129     expr.push_back(clause);
00130 }
00131 
00141 void
00142 ConstraintEvaluator::append_clause(btp_func func, rvalue_list *args)
00143 {
00144     Clause *clause = new Clause(func, args);
00145 
00146     expr.push_back(clause);
00147 }
00148 
00156 void
00157 ConstraintEvaluator::append_constant(BaseType *btp)
00158 {
00159     constants.push_back(btp);
00160 }
00161 
00162 class func_name_is
00163 {
00164 private:
00165     const string d_name;
00166 
00167 public:
00168     func_name_is(const string &name): d_name(name)
00169     {}
00170     bool operator()(const ConstraintEvaluator::function f)
00171     {
00172         return f.name == d_name;
00173     }
00174 };
00175 
00195 #if 1
00196 
00197 void
00198 ConstraintEvaluator::add_function(const string &name, bool_func f)
00199 {
00200     functions.remove_if(func_name_is(name));
00201     function func(name, f);
00202     functions.push_back(func);
00203 }
00204 #endif
00205 
00206 void
00207 ConstraintEvaluator::add_function(const string &name, btp_func f)
00208 {
00209     functions.remove_if(func_name_is(name));
00210     function func(name, f);
00211     functions.push_back(func);
00212 }
00213 
00215 void
00216 ConstraintEvaluator::add_function(const string &name, proj_func f)
00217 {
00218     functions.remove_if(func_name_is(name));
00219     function func(name, f);
00220     functions.push_back(func);
00221 }
00222 #if 1
00223 
00224 bool
00225 ConstraintEvaluator::find_function(const string &name, bool_func *f) const
00226 {
00227     if (functions.empty())
00228         return false;
00229 
00230     for (Functions_citer i = functions.begin(); i != functions.end(); i++) {
00231         if (name == (*i).name && (*f = (*i).b_func)) {
00232             return true;
00233         }
00234     }
00235 
00236     return false;
00237 }
00238 #endif
00239 
00240 bool
00241 ConstraintEvaluator::find_function(const string &name, btp_func *f) const
00242 {
00243     if (functions.empty())
00244         return false;
00245 
00246     for (Functions_citer i = functions.begin(); i != functions.end(); i++) {
00247         if (name == (*i).name && (*f = (*i).bt_func)) {
00248             return true;
00249         }
00250     }
00251 
00252     return false;
00253 }
00254 
00256 bool
00257 ConstraintEvaluator::find_function(const string &name, proj_func *f) const
00258 {
00259     if (functions.empty())
00260         return false;
00261 
00262     for (Functions_citer i = functions.begin(); i != functions.end(); i++)
00263         if (name == (*i).name && (*f = (*i).p_func)) {
00264             return true;
00265         }
00266 
00267     return false;
00268 }
00270 
00273 bool
00274 ConstraintEvaluator::functional_expression()
00275 {
00276     if (expr.empty())
00277         return false;
00278 
00279     Clause *cp = expr[0] ;
00280     return cp->value_clause();
00281 }
00282 
00284 BaseType *
00285 ConstraintEvaluator::eval_function(DDS &dds, const string &)
00286 {
00287     if (expr.size() != 1)
00288         throw InternalErr(__FILE__, __LINE__,
00289                           "The length of the list of CE clauses is not 1.");
00290 
00291     Clause *cp = expr[0] ;
00292     BaseType *result;
00293     if (cp->value(dds, &result))
00294         return result;
00295     else
00296         return NULL;
00297 }
00298 
00300 bool
00301 ConstraintEvaluator::boolean_expression()
00302 {
00303     if (expr.empty())
00304         return false;
00305 
00306     bool boolean = true;
00307     for (Clause_iter i = expr.begin(); i != expr.end(); i++) {
00308         boolean = boolean && (*i)->boolean_clause();
00309     }
00310 
00311     return boolean;
00312 }
00313 
00314 
00322 bool
00323 ConstraintEvaluator::eval_selection(DDS &dds, const string &)
00324 {
00325     if (expr.empty()) {
00326         DBG(cerr << "No selection recorded" << endl);
00327         return true;
00328     }
00329 
00330     DBG(cerr << "Eval selection" << endl);
00331 
00332     // A CE is made up of zero or more clauses, each of which has a boolean
00333     // value. The value of the CE is the logical AND of the clause
00334     // values. See ConstraintEvaluator::clause::value(...) for information on logical ORs in
00335     // CEs.
00336     bool result = true;
00337     for (Clause_iter i = expr.begin(); i != expr.end() && result; i++) {
00338         // A selection expression *must* contain only boolean clauses!
00339         if (!((*i)->boolean_clause()))
00340             throw InternalErr(__FILE__, __LINE__,
00341                               "A selection expression must contain only boolean clauses.");
00342         result = result && (*i)->value(dds);
00343     }
00344 
00345     return result;
00346 }
00347 
00358 void
00359 ConstraintEvaluator::parse_constraint(const string &constraint, DDS &dds)
00360 {
00361     void *buffer = ce_expr_string(constraint.c_str());
00362     ce_expr_switch_to_buffer(buffer);
00363 
00364     ce_parser_arg arg(this, &dds);
00365 
00366     // For all errors, exprparse will throw Error.
00367     ce_exprparse((void *)&arg);
00368 
00369     ce_expr_delete_buffer(buffer);
00370 }
00371 
00372 } // namespace libdap

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