use std::string_view in dstring

src/util/dstring.h

@@ -66,6 +66,12 @@ class dstringt final
   {
   }
 
+  // this one is not safe for static objects
+  // NOLINTNEXTLINE(runtime/explicit)
+  dstringt(const std::string_view &s) : no(get_string_container()[s])
+  {
+  }
+
   // this one is not safe for static objects
   // NOLINTNEXTLINE(runtime/explicit)
   dstringt(const std::string &s):no(get_string_container()[s])
@@ -102,7 +108,7 @@ class dstringt final
   }
 
   /// equivalent of as_string().starts_with(s)
-  bool starts_with(const std::string &prefix) const
+  bool starts_with(const std::string_view &prefix) const
   {
     return as_string().compare(0, prefix.size(), prefix) == 0;
   }

src/util/string_container.h

@@ -19,30 +19,41 @@ Author: Daniel Kroening, kroening@kroening.com
 #include "memory_units.h"
 #include "string_hash.h"
 
-struct string_ptrt
+class string_ptr_hasht;
+
+class string_ptrt
 {
-  const char *s;
-  size_t len;
+public:
+  explicit string_ptrt(const char *_s);
 
-  const char *c_str() const
+  explicit string_ptrt(const std::string_view &_s)
+    : s(_s.data()), len(_s.size())
   {
-    return s;
   }
 
-  explicit string_ptrt(const char *_s);
-
-  explicit string_ptrt(const std::string &_s):s(_s.c_str()), len(_s.size())
+  explicit string_ptrt(const std::string &_s) : s(_s.data()), len(_s.size())
   {
   }
 
+  // this compares the contents of the string, not the address
   bool operator==(const string_ptrt &other) const;
+
+protected:
+  // The string need not be zero terminated.
+  const char *s;
+  size_t len;
+
+  friend string_ptr_hasht;
 };
 
 // NOLINTNEXTLINE(readability/identifiers)
-class string_ptr_hash
+class string_ptr_hasht
 {
 public:
-  size_t operator()(const string_ptrt s) const { return hash_string(s.s); }
+  size_t operator()(const string_ptrt s) const
+  {
+    return hash_string(s.s, s.len);
+  }
 };
 
 /// Has estimated statistics about string container
@@ -68,6 +79,11 @@ class string_containert
     return get(s);
   }
 
+  unsigned operator[](const std::string_view &s)
+  {
+    return get(s);
+  }
+
   unsigned operator[](const std::string &s)
   {
     return get(s);
@@ -93,12 +109,13 @@ class string_containert
 
 protected:
   // the 'unsigned' ought to be size_t
-  typedef std::unordered_map<string_ptrt, unsigned, string_ptr_hash>
+  typedef std::unordered_map<string_ptrt, unsigned, string_ptr_hasht>
     hash_tablet;
   hash_tablet hash_table;
 
-  unsigned get(const char *s);
-  unsigned get(const std::string &s);
+  unsigned get(const char *);
+  unsigned get(const std::string_view &);
+  unsigned get(const std::string &);
 
   typedef std::list<std::string> string_listt;
   string_listt string_list;

src/util/string_hash.cpp

@@ -11,22 +11,16 @@ Author: Daniel Kroening, kroening@kroening.com
 
 #include "string_hash.h"
 
-size_t hash_string(const std::string &s)
+size_t hash_string(const std::string_view &s)
 {
-  size_t h=0;
-  size_t size=s.size();
-
-  for(unsigned i=0; i<size; i++)
-    h=(h<<5)-h+s[i];
-
-  return h;
+  return hash_string(s.data(), s.size());
 }
 
-size_t hash_string(const char *s)
+size_t hash_string(const char *s, std::size_t len)
 {
-  size_t h=0;
+  std::size_t h = 0;
 
-  for(; *s!=0; s++)
+  for(; len != 0; --len)
     h=(h<<5)-h+*s;
 
   return h;

src/util/string_hash.h

@@ -13,9 +13,10 @@ Author: Daniel Kroening, kroening@kroening.com
 #define CPROVER_UTIL_STRING_HASH_H
 
 #include <string>
+#include <string_view>
 
-size_t hash_string(const std::string &s);
-size_t hash_string(const char *s);
+size_t hash_string(const std::string_view &);
+size_t hash_string(const char *s, std::size_t len);
 
 // NOLINTNEXTLINE(readability/identifiers)
 struct string_hash