xapian-applications/omega/expand.cc

   1 /** @file expand.cc
   2  * @brief Set the query expansion scheme for Omega
   3  */
   4 /* Copyright (C) 2009,2013,2014,2015 Olly Betts
   5  * Copyright (C) 2013 Aarsh Shah
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  20  */
  21
  22 #include <config.h>
  23
  24 #include "expand.h"
  25
  26 #include "stringutils.h"
  27
  28 #include <cstdlib>
  29 #include "safeerrno.h"
  30 #include "common/noreturn.h"
  31
  32 using namespace std;
  33
  34 XAPIAN_NORETURN(static void
  35 parameter_error(const char * param, const string & scheme));
  36
  37 static void
  38 parameter_error(const char * msg, const string & scheme)
  39 {
  40     string m(msg);
  41     m += ": '";
  42     m += scheme;
  43     m += "'";
  44     throw m;
  45 }
  46
  47 static bool
  48 double_param(const char ** p, double * ptr_val)
  49 {
  50     char *end;
  51     errno = 0;
  52     double v = strtod(*p, &end);
  53     if (*p == end || errno) return false;
  54     *p = end;
  55     *ptr_val = v;
  56     return true;
  57 }
  58
  59 #if !XAPIAN_AT_LEAST(1,3,2)
  60 double expand_param_k = 1.0;
  61 #endif
  62
  63 void
  64 set_expansion_scheme(Xapian::Enquire & enq, const map<string, string> & opt)
  65 {
  66     map<string, string>::const_iterator i = opt.find("expansion");
  67     if (i == opt.end()) return;
  68
  69     const string & scheme = i->second;
  70     if (scheme.empty()) return;
  71
  72 #if XAPIAN_AT_LEAST(1,3,2)
  73     if (startswith(scheme, "trad")) {
  74         const char *p = scheme.c_str() + 4;
  75         if (*p == '\0') {
  76             enq.set_expansion_scheme("trad");
  77             return;
  78         }
  79         if (C_isspace((unsigned char)*p)) {
  80             // Initialise k just to silence compiler warning.
  81             double k = 0.0;
  82             if (!double_param(&p, &k))
  83                 parameter_error("Parameter k is invalid", scheme);
  84             if (*p)
  85                 parameter_error("Extra data after first parameter", scheme);
  86             enq.set_expansion_scheme("trad", k);
  87             return;
  88         }
  89     }
  90
  91     if (startswith(scheme, "bo1")) {
  92         const char *p = scheme.c_str() + 3;
  93         if (*p == '\0') {
  94             enq.set_expansion_scheme("bo1");
  95             return;
  96         }
  97         if (C_isspace((unsigned char)*p)) {
  98             throw "No parameters are required for BO1";
  99         }
 100     }
 101 #else
 102     if (startswith(scheme, "trad")) {
 103         const char *p = scheme.c_str() + 4;
 104         if (*p == '\0') {
 105             return;
 106         }
 107         if (C_isspace((unsigned char)*p)) {
 108             // Initialise k just to silence compiler warning.
 109             double k = 0.0;
 110             if (!double_param(&p, &k))
 111                 parameter_error("Parameter k is invalid", scheme);
 112             if (*p)
 113                 parameter_error("Extra data after first parameter", scheme);
 114             expand_param_k = k;
 115             // Avoid "unused parameter" error.
 116             (void)enq;
 117             return;
 118         }
 119     }
 120 #endif
 121
 122     throw "Unknown $opt{expansion} setting: " + scheme;
 123 }