http://snippets.dzone.com/posts Sat, 06 Sep 2008 17:15:33 GMT DZone Snippets: excerpt code http://snippets.dzone.com/posts/show/1131 <code> <br /> ;-- collect-based EXCERPT ---------------------------------- <br /> ; Could also change EXTRACT to accept a block value for WIDTH <br /> ; (renamed to, e.g., SPEC). <br /> ; The dialect allows you to use commas in the block, but how they <br /> ; are interpreted is not how you might think. Coming after a number, <br /> ; they are a valid lexical form, but they denote a decimal! rather <br /> ; than being seen as a separator, which means you can't use them too <br /> ; flexibly. <br /> excerpt: func [ <br /> {Returns the specified items and/or ranges from the series.} <br /> series [series!] <br /> offsets [block!] {Offsets of the items to extract; dialected.} <br /> /only "return sub-block ranges as blocks" <br /> /local <br /> emit-range rules <br /> from* to* index* ; parse vars <br /> ][ <br /> ; always uses ONLY right now; it's a prototype. <br /> collect/only val [ <br /> emit-range: func [start end] [ <br /> start: to integer! start <br /> if number? end [end: to integer! end - start + 1] <br /> val: either end = 'end [copy at series start][ <br /> copy/part at series start end <br /> ] <br /> ] <br /> rules: [ <br /> some [ <br /> opt 'from set from* number! 'to set to* number! ( <br /> emit-range from* to* <br /> ) <br /> | opt 'from set from* number! 'to 'end (emit-range from* 'end) <br /> | 'to set to* number! (emit-range 1 to*) <br /> | set index* number! (val: pick series index*) <br /> | into rules <br /> ] <br /> ] <br /> parse offsets rules <br /> ] <br /> ] <br /> comment { <br /> b: [1 2 3 4 5 6 7 8 9 10 11 12 13 14] <br /> excerpt b [1 3 5] <br /> excerpt b [1 3 to 6 8] <br /> excerpt/only b [1, 3 to 6, 8] <br /> excerpt b [1 [5 to 7] 8] <br /> excerpt/only b [1 (from 5 to 7) 8] <br /> excerpt b [(to 2) [4 to 6] 8, 10, from 12 to end] <br /> excerpt/only b [to 2, 4 to 6, 8, 10, (12 to end)] <br /> ; Can't use a comma after 'end <br /> excerpt/only b [to 2 to 6 8 10 to end 12 to end] <br /> excerpt/only b [to 2, to 6, 8 [10 to end] 12 to end] <br /> excerpt/only trim { <br /> REBOL is my favorite language <br /> } [ <br /> to 5, 10 to 11, 13, 14, 15, 22 to end <br /> ] <br /> excerpt/only to binary! {REBOL is my favorite language} [ <br /> to 5, 10 to 11, 13, 14, 15, 22 to end <br /> ] <br /> } <br /></code> Tue, 10 Jan 2006 06:27:53 GMT http://snippets.dzone.com/posts/show/1131 gregg.irwin (Gregg Irwin)