Syntax Color: Utilities

The "syntax-color" collection provides the underlying data structures and some helpful utilities for the color:text% class of the Framework: PLT GUI Application Framework.

1 Parenthesis Matching

(require syntax-color/paren-tree)

paren-tree% : class?

superclass: object%

Parenthesis matching code built on top of token-tree%.

2 Scheme Lexer

(require syntax-color/scheme-lexer)

(scheme-lexer in)   →   (or/c string? eof-object?) symbol? (or/c symbol? false/c) (or/c number? false/c) (or/c number? false/c)

in : input-port?

A lexer for Scheme, including reader extensions (Reader Extension), built specifically for color:text%.

The scheme-lexer function returns 5 values:

• Either a string containing the matching text or the eof object. Block comments and specials currently return an empty string. This may change in the future to other string or non-string data.

• A symbol in '(error comment sexp-comment white-space constant string no-color parenthesis other symbol eof).

• A symbol in '(|(| |)| |[| |]| |{| |}|) or #f.

• A number representing the starting position of the match (or #f if eof).

• A number representing the ending position of the match (or #f if eof).

3 Default lexer

(require syntax-color/default-lexer)

(default-lexer in)   →   (or/c string? eof-object?) symbol? (or/c symbol? false/c) (or/c number? false/c) (or/c number? false/c)

in : input-port?

A lexer that only identifies (, ), [, ], {, and } built specifically for color:text%.

default-lexer returns 5 values:

• Either a string containing the matching text or the eof object. Block specials currently return an empty string. This may change in the future to other string or non-string data.

• A symbol in '(comment white-space no-color eof).

• A symbol in '(|(| |)| |[| |]| |{| |}|) or #f.

• A number representing the starting position of the match (or #f if eof).

• A number representing the ending position of the match (or #f if eof).

4 Splay Tree for Tokenization

(require syntax-color/token-tree)

token-tree% : class?

superclass: object%

A splay-tree class specifically geared for the task of on-the-fly tokenization. Instead of keying nodes on values, each node has a length, and they are found by finding a node that follows a certain total length of preceding nodes.

FIXME: many methods are not yet documented.

(new token-tree% [len len] [data data])

→ (is-a?/c token-tree%)

len : (or/c exact-nonnegative-integer? fasle/c)

data : any/c

Creates a token tree with a single element.

(send a-token-tree get-root) → (or/c node? false/c)

Returns the root node in the tree.

(send a-token-tree search! key-position) → void?

key-position : natural-number/c

Splays, setting the root node to be the closest node to offset key-position (i.e., making the total length of the left tree at least key-position, if possible).

(node? v) → boolean?   v : any/c

(node-token-length n) → natural-number/c   n : node?

(node-token-data n) → any/c   n : node?

(node-left-subtree-length n) → natural-number/c   n : node?

(node-left n) → (or/c node? false/c)   n : node?

(node-right n) → (or/c node? false/c)   n : node?

Functions for working with nodes in a token-tree%.

(insert-first! tree1 tree2) → void?

tree1 : (is-a?/c token-tree%)

tree2 : (is-a?/c token-tree%)

Inserts tree1 into tree2 as the first thing, setting tree2’s root to #f.

(insert-last! tree1 tree2) → void?

tree1 : (is-a?/c token-tree%)

tree2 : (is-a?/c token-tree%)

Inserts tree1 into tree2 as the last thing, setting tree2’s root to #f.

(insert-last-spec! tree n v) → void?

tree : (is-a?/c token-tree%)

n : natural-number/c

v : any/c

Same as (insert-last! tree (new token-tree% [length n] [data v])). This optimization is important for the colorer.