error: expected primary-expression before '<' token - c++

Question

I compiled the below code with gcc4.4.1 on linux:-
#include "glob.h"
#include "netlist.h"
#include "netlist_params.h"
#include "netlist_abbrev.h"
#include "lvs_util.h"
#include "lvs_report.h"
#include "lvs_data.h"
#include "compare_opts.h"
#include "flatten.h"
#include <stdio.h>
#include <string.h>
#include <iostream>
#include <math.h>
#include "hash.h"
static THREAD_PRIVATE NlStringVec* ext_str_tab_v;
static THREAD_PRIVATE const char* ext_str_tab_s1;
static THREAD_PRIVATE const char* ext_str_tab_s2;
int Netlist::ExtStrHash::operator () (NlString i) const {
if (i.is_valid())
ext_str_tab_s1 = (*ext_str_tab_v)[i];
return Hash<const char*>::operator()(ext_str_tab_s1);
}
Error:-
netlist_back_1.C: In member function 'int Netlist::ExtStrHash::operator()(NlString) const':
netlist_back_1.C:24: error: expected primary-expression before '<' token
netlist_back_1.C:24: error: expected primary-expression before 'const'
netlist_back_1.C:24: error: expected ';' before 'const'
netlist_back_1.C:24: error: expected unqualified-id before '>' token
netlist_back_1.C:24: error: expected initializer before '>' token
Definition of hash in file hash.h:-
namespace Hash {
// template <class Key> struct Hash { };
#define DECL_SIMPLE_HASH(type) \
template <> \
struct Hash<type> { \
unsigned int operator() (type x) const { return x; } \
}
DECL_SIMPLE_HASH(signed char);
DECL_SIMPLE_HASH(unsigned char);
DECL_SIMPLE_HASH(signed short);
DECL_SIMPLE_HASH(unsigned short);
DECL_SIMPLE_HASH(signed int);
DECL_SIMPLE_HASH(unsigned int);
DECL_SIMPLE_HASH(signed long);
DECL_SIMPLE_HASH(unsigned long);
DECL_SIMPLE_HASH(signed long long);
DECL_SIMPLE_HASH(unsigned long long);
#undef DECL_SIMPLE_HASH
template <>
class Hash<const char*> {
static const int M = 61; // 5;
public:
unsigned int operator() (const char* s) const {
// case insensitive, so sensitivity can be turned on/off without
// effecting hash #.
unsigned h = 0;
char c;
while (c = *s++) {
if (c >= 'A' && c <= 'Z')
c = c - 'A' + 'a';
h = M*h + c;
}
return h;
}
};
template <> struct Hash<char*> : public Hash<const char*> {};
}
EDIT:: I needed to include the namespace. Working on other's code lead to foolish mistakes.
Thanks for vote down and help. :)
Any help is appreciated. Thanks.

Answer 1

As far as I can see:
You're not including "hash.h"
You've commented out the declaration of the Hash template, leaving only the explicit specialisations. You still need to declare the template, even if you don't define the generic version.
The Hash template is inside a namespace Hash, but you neither use that namespace nor fully qualify the template name. (By the way, it's not a very good idea to use the same name for a namespace and a class; it can lead to ambiguities).
You're trying to call a non-static operator() as if it's static; you want something more like return Hash<const char*>()(ext_str_tab_s1);.
So it's no surprise that Hash is not recognised as a template name (although it has to be said that the error message is not very helpful).

Answer 2

There are few possible options :
you didn't include the header where the Hash template is defined
the template Hash is in different namespace

Answer 3

Hash is a namespace. Namespaces can't have template parameters.
Don't give types and namespaces the same name.