NAME¶

TextBuffer - operations on unstructured text

SYNOPSIS¶

#include <InterViews/textbuffer.h>

DESCRIPTION¶

TextBuffer defines common editing, searching, and text movement operations on a buffer of unstructured text. Text positions are specified by an index into the buffer and logically refer to positions between characters. For example, the position referred to by the index 0 is before the first character in the text. Indices can be compared for equality or ordering, but they should not be used to directly access the buffer because TextBuffer might rearrange the text to improve the efficiency of some operations.

PUBLIC OPERATIONS¶

TextBuffer(char* buffer, int length, int size)

~TextBuffer()

Create or destroy an instance of TextBuffer. All operations on the text contained in buffer should be performed through TextBuffer functions. The text is assumed to be of length length, and the total available buffer size is size.

int Search(Regexp* regexp, int index, int range, int stop)

int ForwardSearch(Regexp* regexp, int index)

int BackwardSearch(Regexp* regexp, int index)

Search for a match with the regular expression regexp, beginning at position index. Search searches the part of the buffer specified by range and stop and returns the index of the beginning of the matched text. Positive values of range specify forward searches, and negative values specify backward searches. In either case, the matched text will not extend beyond the position given by stop. ForwardSearch searches for matches from index to the end of the text and returns the index of the end of the match. BackwardSearch searches from index to the start of the text and returns the index of the beginning of the match. All three functions return a negative number if there was no match.

int Match(Regexp* regexp, int index, int stop)

boolean ForwardMatch(Regexp* regexp, int index)

boolean BackwardMatch(Regexp* regexp, int index)

Attempt to match the regular expression regexp at the position index. Match returns the length of the matching string, or a negative number if there was no match. Matching will not succeed beyond the position given by stop. ForwardMatch looks for a match that begins at index. BackwardMatch looks for a match that ends at index.

int Insert(int index, const char* string, int count)

int Delete(int index, int count)

int Copy(int index, char* buffer, int count)

Edit the text in the buffer. Insert inserts count characters from string at the position index. It returns the actual number of characters inserted, which might be less than count if there is insufficient space in the buffer. Delete deletes count characters from the buffer. A positive count deletes characters after index, and a negative value deletes character before index. Delete returns the actual number of characters deleted, which might be less than count if index is near the beginning or the end of the text. Copy copies count characters into buffer. A positive count copies characters after index and a negative count copies characters before index. Count returns the actual number of characters copied. It is the caller's responsibility to ensure that buffer contains sufficient space for the copied text.

int Height()

int Width()

int Length()

Return information about the text. Height returns the number of lines in the text, Width returns the number of characters in the longest line, and Length returns the total number of characters.

const char* Text()

const char* Text(int index)

const char* Text(int index1, int index2)

char Char (int index)

Access the contents of the text. Char returns the character immediately following index. The three Text calls return pointers to character strings representing the text. They make various guarantees about the format of the returned string. With no parameters, Text returns a pointer to a string that contains the entire text of the buffer. With a single parameter the string contains at least the text from index to the end of the line. With two parameters, the returned string contains at least the text between index1 and index2. In any case, the returned string should be considered temporary and its contents subject to change. To maximize efficiency, you should prefer the more restricted forms of Text.

int LineIndex(int line)

int LinesBetween(int index1, int index2)

int LineNumber(int index)

int LineOffset (int index)

Map between text indices and line and offset positions. LineIndex returns the index of the beginning of line line. LineNumber returns the number of the line that contains index. LineOffset returns the offset of index from the beginning of its containing line. LinesBetween returns the difference between the numbers of the lines containings index1 and index2; a return value of zero indicates that index1 and index2 are on the same line, and a positive value indicates that the line containing index2 is after the line containing index1. Lines are numbered starting from zero.

int PreviousCharacter(int index)

int NextCharacter(int index)

Return the index immediately following or preceding index. The returned value is never before the beginning or after the end of the text.

boolean IsBeginningOfText(int index)

int BeginningOfText()

boolean IsEndOfText(int index)

int EndOfText()

Return the index of the beginning or end of the text, or query whether index is at the beginning or end of the text.

boolean IsBeginningOfLine(int index)

int BeginningOfLine(int index)

int BeginningOfNextLine(int index)

boolean IsEndOfLine(int index)

int EndOfLine(int index)

int EndOfPreviousLine(int index)

Return information about the line structure of the text around index. BeginningOfLine returns the index of the beginning of the line containing index. BeginningOfNextLine returns the index of the beginning of the next line that begins after index. EndOfLine returns the index of the end of the line containing index. EndOfPreviousLine returns the index of the end of the last line that ends before index. The beginning of a line is logically immediately after a newline character, and the end of a line is logically immediately before a newline character. The beginning and end of the text are considered to be the beginning and end of the first and last lines, respectively.

boolean IsBeginningOfWord(int index)

int BeginningOfWord(int index)

int BeginningOfNextWord(int index)

boolean IsEndOfWord(int index)

int EndOfWord(int index)

int EndOfPreviousWord(int index)

Return information about the word structure of the text around index. BeginningOfWord returns the index of the beginning of the word containing index. BeginningOfNextWord return the index of the beginning of the nest word that begins after index. EndOfWord returns the index of the end of the word that contains index. EndOfPreviousWord returns the index of the end of the last word that ends before index. A word is defined as a sequence of alpha-numeric characters. The beginning and end of the text are considered to be the beginning and end of the first and last words, respectively.

SEE ALSO¶

Regexp(3I)