IndentDedentInputBuffer (parboiled-core

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org.parboiled.buffers
Class IndentDedentInputBuffer

java.lang.Object
  org.parboiled.buffers.IndentDedentInputBuffer

All Implemented Interfaces:: InputBuffer

public class IndentDedentInputBuffer
extends java.lang.Object
implements InputBuffer
extends java.lang.Object
implements InputBuffer

Special, immutable InputBuffer implementation for indentation based grammars.

This InputBuffer collapses all space and tab characters at the beginning of a text line into either nothing (if the line has the same indentation level as the previous line), a special Chars.INDENT character (if the line has a greater indentation level than the previous line) or one or more Chars.DEDENT characters (if the line has a lower indentation level than the previous line).

Blank lines (lines containing nothing but whitespace) are removed from the input and the buffer can, optionally, remove line comments (i.e. comments that start with a predefined character sequence and go to the end of the line).

This means that the highest index of this InputBuffer is probably smaller than that of the original input text buffer, since all line indentations and blank lines have been collapsed. However, the implementation will make sure that getPosition(int), extract(int, int), etc. will work as expected and always return the "correct" result from the underlying, original input buffer.

If the input contains illegal indentation the buffer throws an IllegalIndentationException during construction

Constructor Summary
`IndentDedentInputBuffer(char[] input, int tabStop, java.lang.String lineCommentStart, boolean strict)` Creates a new IndentDedentInputBuffer around the given char array.

Method Summary
`char`	`charAt(int index)` Returns the character at the given index.
`java.lang.String`	`extract(IndexRange range)` Constructs a new `String` from all character covered by the given IndexRange.
`java.lang.String`	`extract(int start, int end)` Constructs a new `String` from all character between the given indices.
`java.lang.String`	`extractLine(int lineNumber)` Constructs a new `String` containing all characters with the given line number except for the trailing newline.
`int`	`getLineCount()` Returns the number of lines in the input buffer.
`int`	`getOriginalIndex(int index)` Translates the given index from the scope of this InputBuffer to the scope of the original, underlying char array.
`Position`	`getPosition(int index)` Returns the line and column number of the character with the given index encapsulated in a `Position` object.
`boolean`	`test(int index, char[] characters)` Determines whether the characters starting at the given index match the ones from the given array (in order).

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

IndentDedentInputBuffer

public IndentDedentInputBuffer(char[] input,
                               int tabStop,
                               java.lang.String lineCommentStart,
                               boolean strict)

Creates a new IndentDedentInputBuffer around the given char array. Note that for performance reasons the given char array is not defensively copied.

Parameters:: input - the input text.; tabStop - the number of characters in a tab stop.; lineCommentStart - the string starting a line comment or null, if line comments are not defined; strict - signals whether the buffer should throw an IllegalIndentationException on "semi-dedents", if false the buffer silently accepts these
Throws:: IllegalIndentationException - if the input contains illegal indentations and the strict flag is set

Method Detail