Support StringView in SQLite

Author: mattgodbolt

src/Sqlite.cpp

@@ -74,20 +74,20 @@ bool Sqlite::Statement::step() {
 }
 
 Sqlite::Statement &Sqlite::Statement::bindBlob(
-        const std::string &param, const void *data, size_t length) {
+        StringView param, const void *data, size_t length) {
     R(sqlite3_bind_blob(statement_, P(param), data, length, SQLITE_TRANSIENT));
     return *this;
 }
 
-Sqlite::Statement &Sqlite::Statement::bindInt64(const std::string &param,
+Sqlite::Statement &Sqlite::Statement::bindInt64(StringView param,
                                                 int64_t data) {
     R(sqlite3_bind_int64(statement_, P(param), data));
     return *this;
 }
 
-Sqlite::Statement &Sqlite::Statement::bindString(const std::string &param,
-                                                 const std::string &data) {
-    R(sqlite3_bind_text(statement_, P(param), data.c_str(), data.size(),
+Sqlite::Statement &Sqlite::Statement::bindString(StringView param,
+                                                 StringView data) {
+    R(sqlite3_bind_text(statement_, P(param), data.begin(), data.length(),
                         SQLITE_TRANSIENT));
     return *this;
 }
@@ -108,11 +108,13 @@ std::string Sqlite::Statement::columnName(int index) const {
     return sqlite3_column_name(statement_, index);
 }
 
-int Sqlite::Statement::P(const std::string &param) const {
-    auto index = sqlite3_bind_parameter_index(statement_, param.c_str());
+int Sqlite::Statement::P(StringView param) const {
+    std::string asStringStorage;
+    auto index = sqlite3_bind_parameter_index(statement_,
+                                              param.c_str(asStringStorage));
     if (index == 0)
         throw std::runtime_error(
-                "Unable to find bound parameter '" + param + "'");
+                "Unable to find bound parameter '" + param.str() + "'");
     return index;
 }
 

src/Sqlite.h

@@ -1,8 +1,11 @@
 #pragma once
 
+#include "StringView.h"
+
 #include <cstdint>
 #include <string>
 #include <sqlite3.h>
+#include <unordered_map>
 #include <vector>
 
 class Log;
@@ -56,11 +59,10 @@ class Sqlite {
         Statement &operator=(Statement &&other);
 
         Statement &reset();
-        Statement &bindInt64(const std::string &param, int64_t data);
-        Statement &bindBlob(const std::string &param, const void *data,
+        Statement &bindInt64(StringView param, int64_t data);
+        Statement &bindBlob(StringView param, const void *data,
                             size_t length);
-        Statement &bindString(const std::string &param,
-                              const std::string &string);
+        Statement &bindString(StringView param, StringView string);
 
         bool step();
 
@@ -72,7 +74,7 @@ class Sqlite {
         std::vector<uint8_t> columnBlob(int index) const;
 
     private:
-        int P(const std::string &param) const;
+        int P(StringView param) const;
     };
 
     Statement prepare(const std::string &sql) const;

src/StringView.h

@@ -38,5 +38,15 @@ class StringView {
         return length_ ? std::string(begin_, length_) : std::string();
     }
 
+    // Return a zero-terminated c-style string, using the StringView storage
+    // itself if possible, else placing the zero-terminated string in the
+    // supplied std::string. Only works for strings without embedded nuls.
+    const char *c_str(std::string &storage) const {
+        if (length_ == 0) return "";
+        if (begin_[length_] == '\0') return begin_;  // already zero-terminated
+        storage.assign(begin_, length_);
+        return storage.c_str();
+    }
+
     friend std::ostream &operator<<(std::ostream &o, const StringView &sv);
 };