Add minimal version of class Fl_String

This class will be used in fl_input_str() and fl_password_str().

Todo: add missing documentation ...

FL/Fl_String.H

@@ -0,0 +1,114 @@
+//
+// Basic Fl_String header for the Fast Light Tool Kit (FLTK).
+//
+// Copyright 2021 by Bill Spitzak and others.
+//
+// This library is free software. Distribution and use rights are outlined in
+// the file "COPYING" which should have been included with this file.  If this
+// file is missing or damaged, see the license at:
+//
+//     https://www.fltk.org/COPYING.php
+//
+// Please see the following page on how to report bugs and issues:
+//
+//     https://www.fltk.org/bugs.php
+//
+
+#ifndef _FL_FL_STRING_H_
+#define _FL_FL_STRING_H_
+
+/** \file FL/Fl_String.H
+  Basic Fl_String class for FLTK.
+*/
+
+/**
+  Fl_String is the basic string class for FLTK.
+
+  In this version Fl_String can be used to store strings, copy strings,
+  and move strings. There are no string manipulation methods yet.
+
+  Fl_String can hold the value of an Fl_Input widget including \e nul bytes
+  if the constructor Fl_String(const char *str, int size) is used.
+
+  Assignment and copy constructors \b copy the string value such that the
+  source string can be freed immediately after the assignment.
+
+  The string value() can be an empty string \c "" or \c NULL.
+
+  If value() is not \c NULL it is guaranteed that the string is terminated by
+  a trailing \c nul byte even if the string contains embedded \c nul bytes.
+
+  The method size() returns the full string size, whether the string contains
+  embedded \c nul bytes or not. The special method slen() returns 0 if value()
+  is \c NULL, otherwise the same as \c strlen() would do.
+
+  Examples:
+  \code
+  Fl_String np(NULL);
+  printf("  np    : value = %p, size = %d, slen = %d\n", np.value(), np.size(), np.slen());
+  Fl_String empty("");
+  printf("  empty : value = %p, size = %d\n", empty.value(), empty.size());
+  Fl_String fltk("FLTK");
+  Fl_Input i(0, 0, 0, 0);
+  i.value("abc\0def", 7);
+  Fl_String str(i.value(), i.size());
+  printf("  str   : strlen = %lu, size = %d, capacity = %d\n",
+         strlen(str.value()), str.size(), str.capacity());
+
+  Output:
+
+  np    : value = (nil), size = 0, slen = 0
+  empty : value = 0x562840befbf0, size = 0
+  str   : strlen = 3, size = 7, capacity = 15
+  \endcode
+
+  \since 1.4.0
+
+  \todo Complete documentation of class Fl_String
+*/
+
+class Fl_String {
+private:
+  int size_;
+  char *value_;
+  int capacity_;
+
+public:
+  Fl_String();
+  Fl_String(const char *str);
+  Fl_String(const char *str, int size);
+
+  // copy constructor
+  Fl_String(const Fl_String &in);
+
+  // copy assignment operator
+  Fl_String& operator=(const Fl_String &in);
+
+  // assignment operator for 'const char *'
+  Fl_String& operator=(const char *in);
+
+  virtual ~Fl_String();
+
+private:
+  void init();
+  void alloc_buf(int size);
+  void release();
+
+public:
+  void value(const char *str);
+  void value(const char *str, int slen);
+
+  const char *value() const { return value_; }
+  int size() const { return size_; }
+
+  int slen() const;
+  int capacity() const;
+
+  // ==================================  DEBUG  ==================================
+
+  void debug(const char *info) const;           // output string info
+  void hexdump(const char *info) const;         // output info + hexdump
+
+}; // class Fl_String
+
+#endif // _FL_FL_STRING_H_

src/CMakeLists.txt

@@ -78,6 +78,7 @@ set (CPPFILES
   Fl_Single_Window.cxx
   Fl_Slider.cxx
   Fl_Spinner.cxx
+  Fl_String.cxx
   Fl_Sys_Menu_Bar.cxx
   Fl_System_Driver.cxx
   Fl_Table.cxx

src/Fl_String.cxx

@@ -0,0 +1,159 @@
+//
+// Basic Fl_String class for the Fast Light Tool Kit (FLTK).
+//
+// Copyright 2021 by Bill Spitzak and others.
+//
+// This library is free software. Distribution and use rights are outlined in
+// the file "COPYING" which should have been included with this file.  If this
+// file is missing or damaged, see the license at:
+//
+//     https://www.fltk.org/COPYING.php
+//
+// Please see the following page on how to report bugs and issues:
+//
+//     https://www.fltk.org/bugs.php
+//
+
+#include <FL/Fl_String.H>
+
+#include <stdio.h>
+#include <string.h>
+
+/** \file src/Fl_String.cxx
+  Basic Fl_String class for FLTK.
+*/
+
+static int string_count;
+
+Fl_String::Fl_String() {
+  string_count++;
+  init();
+  // debug("created ()");
+}
+
+Fl_String::Fl_String(const char *str) {
+  string_count++;
+  init();
+  value(str);
+  // debug("created (str)");
+}
+
+Fl_String::Fl_String(const char *str, int size) {
+  string_count++;
+  init();
+  value(str, size);
+  // debug("created (str, size)");
+}
+
+void Fl_String::init() {
+  size_ = 0;
+  value_ = 0;
+  capacity_ = 0;
+}
+
+// copy constructor
+Fl_String::Fl_String(const Fl_String &in) {
+  string_count++;
+  init();
+  value(in.value(), in.size());
+  // debug("copied (c'tor)");
+}
+
+// copy assignment operator
+Fl_String& Fl_String::operator=(const Fl_String &in) {
+  if (this == &in)
+    return *this;
+  value(in.value(), in.size());
+  // debug("copy assigned");
+  return *this;
+}
+
+// assignment operator for 'const char *'
+Fl_String& Fl_String::operator=(const char *in) {
+  value(in);
+  // debug("*STRING* assigned");
+  return *this;
+}
+
+Fl_String::~Fl_String() {
+  string_count--;
+  // debug("~Fl_String()");
+  delete[] value_;
+}
+
+void Fl_String::alloc_buf(int size) {
+  if (size < 0)
+    return;
+  if (size > 0 && size <= capacity_)
+    return;
+  if (capacity_ > 0)
+    return;
+
+  int new_size = (size + 1 + 15) & (~15); // round upwards
+  char *new_value = new char[new_size];
+  capacity_ = new_size - 1;
+
+  size_ = 0;
+  delete[] value_;
+  value_ = new_value;
+}
+
+void Fl_String::value(const char *str) {
+  value(str, str ? strlen(str) : 0);
+}
+
+int Fl_String::slen() const {
+  if (!value_) return 0;
+  return (int)strlen(value_);
+}
+
+void Fl_String::value(const char *str, int len) {
+  if (str) {
+    alloc_buf(len);
+    size_ = len;
+    memcpy(value_, str, size_);
+    value_[size_] = '\0';
+  } else {            // str == NULL
+    size_ = 0;        // ignore len !
+    delete[] value_;  // free buffer
+    value_ = NULL;    // set null pointer (!)
+    capacity_ = 0;    // reset capacity
+  }
+}
+
+int Fl_String::capacity() const {
+  return capacity_; // > 0 ? capacity_ - 1 : capacity_;
+}
+
+void Fl_String::release() {
+  delete[] value_;
+  value_ = 0;
+  size_ = 0;
+  capacity_ = 0;
+}
+
+// =============================  DEBUG  =============================
+
+static const char fl_string_debug = 0;
+
+void Fl_String::debug(const char *info) const {
+  if (fl_string_debug) {
+    printf("Fl_String[%2d] '%-20s': %p, value = %p (%d/%d): '%s'.\n",
+          string_count, info, this, value_, size_, capacity_, value_);
+  }
+}
+
+void Fl_String::hexdump(const char *info) const {
+  if (fl_string_debug) {
+    debug(info);
+    for (int i = 0; i < size_; i++) {
+      if ((i & 15) == 0) {
+        if (i > 0) printf("\n");
+        printf("  [%04x %4d] ", i, i);
+      } else if ((i & 3) == 0)
+        printf(" ");
+      printf(" %02x", (unsigned char)value_[i]);
+    }
+    printf("\n");
+  }
+}

src/Makefile

@@ -80,6 +80,7 @@ CPPFILES = \
 	Fl_Single_Window.cxx \
 	Fl_Slider.cxx \
 	Fl_Spinner.cxx \
+	Fl_String.cxx \
 	Fl_Sys_Menu_Bar.cxx \
 	Fl_System_Driver.cxx \
 	Fl_Table.cxx \