Commit 054a0048b91b7ccb5051418ab1869b51ca9b4721 - Lexeduct

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README.md less more

20	20
21	21	So, for example,
22	22
23		lexeduct.js upper <input.txt
	23	echo 'Hello!' \| lexeduct.js upper
24	24
25		and an uppercased version of the contents of `input.txt` will be dumped to
26		the standard output.
	25	will dump the string `HELLO!` to standard output.
27	26
28	27	You can of course use shell pipelines to compose filters:
29	28

41	40	of possible text filters that can be composed. Or at least, more than four.
42	41
43	42	Each filter is in a seperate Javascript file in the `src/filter` directory
44		which exports, node-style, a single function called `filter` which takes
45		two arguments. For example, here is the source of the `upper` filter, found
	43	which exports, node-style, a single function called `makeFilter` which takes
	44	a configuration object and returns a filter function. The filter function
	45	takes two arguments: the current string of text to process, and (optionally)
	46	an object which can be used to store ancillary state. It should return
	47	either a string, or null (not yet supported), or an array of strings (not yet
	48	supported.)
	49
	50	As a simple example, here is the source of the `upper` filter, found
46	51	in `src/filter/upper.js`:
47	52
48	53	module.exports = {
49		filter: function(line, state) {
50		return line.toUpperCase();
	54	makeFilter: function(cfg) {
	55	return function(line, state) {
	56	return line.toUpperCase();
	57	};
51	58	}
52	59	};
53	60
54	61	`state` is an object whose members may be read or written to store ancillary
55	62	state. (Doing so will make it an 'impure' pipeline.)
56
57		NOTE: this interface is likely to change real soon now, to support passing
58		parameters to filters.
59	63
60	64	TODO
61	65	----

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src/filter/double-space.js less more

0	0	module.exports = {
1		filter: function(line, state) {
2		var s = "";
3		for (var i = 0; i < line.length; i++) {
4		s += line.charAt(i) + " ";
5		}
6		return s;
	1	makeFilter: function(cfg) {
	2	return function(line, state) {
	3	var s = "";
	4	for (var i = 0; i < line.length; i++) {
	5	s += line.charAt(i) + " ";
	6	}
	7	return s;
	8	};
7	9	}
8	10	};

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src/filter/insert-vowels.js less more

0	0	module.exports = {
1		filter: function(line, state) {
2		var s = "";
3		var vowels = "aeiou";
4		for (var i = 0; i < line.length; i++) {
5		s += line.charAt(i) + vowels.charAt(Math.floor(Math.random() * vowels.length));
6		}
7		return s;
	1	makeFilter: function(cfg) {
	2	return function(line, state) {
	3	var s = "";
	4	var vowels = "aeiou";
	5	for (var i = 0; i < line.length; i++) {
	6	s += line.charAt(i) + vowels.charAt(Math.floor(Math.random() * vowels.length));
	7	}
	8	return s;
	9	};
8	10	}
9	11	};

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src/filter/lower.js less more

0	0	module.exports = {
1		filter: function(line, state) {
2		return line.toLowerCase();
	1	makeFilter: function(cfg) {
	2	return function(line, state) {
	3	return line.toLowerCase();
	4	};
3	5	}
4	6	};

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src/filter/upper.js less more

0	0	module.exports = {
1		filter: function(line, state) {
2		return line.toUpperCase();
	1	makeFilter: function(cfg) {
	2	return function(line, state) {
	3	return line.toUpperCase();
	4	};
3	5	}
4	6	};

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src/lexeduct.js less more

15	15	};
16	16	};
17	17
	18	/*
	19	* Load the filters that were specified on the command line.
	20	*/
18	21	for (var i = 0; i < args.length; i++) {
	22	// TODO: parse filter parameters off end of args[i]
19	23	var module = require('./filter/' + args[i]);
	24	var loadedFilter = module.makeFilter({});
20	25	if (filter === undefined) {
21		filter = module.filter;
	26	filter = loadedFilter;
22	27	} else {
23		filter = compose(module.filter, filter);
	28	filter = compose(loadedFilter, filter);
24	29	}
25	30	}
26	31