# strbuf.h | documentation

    #charset "us-ascii"
    #pragma once

    /*
     *   Copyright 2009 Michael J. Roberts.
     *
     *   This file is part of TADS 3.
     *
     *   This module defines the StringBuffer intrinsic class.  StringBuffer is
     *   essentialy a mutable version of String: you can append, insert, replace,
     *   and delete characters in place, without creating new objects as a
     *   result.  This is useful for complex string constructions that involve
     *   many incremental steps, since it avoids the repeated memory allocation
     *   and string copying operations that would be involved if the intermediate
     *   steps were performed with ordinary String objects.
     */

    /*
     *   A StringBuffer is a mutable character string object.  You can insert,
     *   append, delete, and replace characters in the buffer in place.  These
     *   operations don't create new objects as they do with ordinary strings,
     *   but simply modify the existing StringBuffer object's contents.
     *
     *   The object manages memory automatically.  When you first create the
     *   object, it allocates an initial buffer to hold its character contents.
     *   You can specify the initial buffer size with a constructor argument, or
     *   simply let the object pick a default.  As you add text to the buffer,
     *   the object automatically allocates more memory as needed to accommodate
     *   the added text.  The maximum size for the string contained in the buffer
     *   is about 32000 characters.
     *
     *   Construction: new StringBuffer() creates a buffer with default initial
     *   size values.  new StringBuffer(length, increment) specifies the initial
     *   buffer size in characters ('length'), and the minimum number of
     *   characters to add to the buffer each time it's automatically expanded
     *   ('increment').
     *
     *   Passing a StringBuffer to an internal function or method that takes a
     *   String argument, such as tadsSay(), will automatically convert the
     *   object to a string.  To explicitly convert a StringBuffer to an ordinary
     *   String, use the toString() function.  You can also create an ordinary
     *   string from a section of the buffer using the substr() method.
     */
    intrinsic class StringBuffer 'stringbuffer/030000'
    {
        /*
         *   Get the length in characters of the current text in the buffer.
         */
        length();

        /*
         *   Retrieve the Unicode character value of the character at the given
         *   index.  Returns an integer with the Unicode value.  If idx is
         *   negative, it's an index from the end of the string: -1 is the last
         *   character, -2 is the second to last, etc.
         */
        charAt(idx);

        /*
         *   Append text to the current contents of the buffer.  This adds the
         *   new text at the end of the current text.  The value is automatically
         *   converted to a string if possible; this includes numbers and
         *   true and nil values.
         */
        append(str);

        /*
         *   Insert text into the buffer just before the character at the given
         *   index.  The first character is at index 1, so to insert the new text
         *   before the first current character, insert at index 1.  If the index
         *   is past the end of the current text, this has the same effect as
         *   append().  A negative value indexes from the end of the string.  The
         *   text is automatically converted to a string if possible.
         */
        insert(txt, idx);

        /*
         *   Copy text into the buffer, starting at the given index (the first
         *   character in the buffer is at index 1).  Overwrites any text
         *   currently in the buffer at this point.
         */
        copyChars(txt, idx);

        /*
         *   Delete the given text.  This deletes 'len' characters starting at
         *   the given index (the first character is at index 1).  If the length
         *   is omitted, the portion from idx to the end of the string is
         *   deleted.  A negative idx value indexes from the end of the string.
         */
        deleteChars(idx, len?);

        /*
         *   Splice text.  This deletes 'len' characters starting at the given
         *   index (the first character is at index 1), and replaces them with
         *   the given new text.  If the new text is nil, this simply deletes the
         *   old characters without inserting anything new.  If 'len' is zero,
         *   simply inserts the new text without deleting any old text.  A
         *   negative idx value indexes from the end of the string.  The 'str'
         *   value is automatically converted to a string if possible.
         */
        splice(idx, len, str);

        /*
         *   Retrieve the substring of the buffer starting at the given index and
         *   running for the given character length.  If the length is omitted,
         *   everything from the starting index to the end of the buffer is
         *   included in the result string.  A negative value for 'idx' indexes
         *   from the end of the string.
         */
        substr(idx, len?);
    }

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