X-Git-Url: https://git.yukkurigames.com/?p=string-lerp.git;a=blobdiff_plain;f=string-lerp.js;h=8e3ef6417ab7fb846538f5bc57348516fcef9753;hp=fdf7df8765be728d4ba6c77bbaffd746a3dbe09b;hb=203ddaf6c8bc3326257cfeeda9a01752fbc7ab5c;hpb=8ca7031e6a8079cecb8e06186c0d50cb2ab0aceb diff --git a/string-lerp.js b/string-lerp.js index fdf7df8..8e3ef64 100644 --- a/string-lerp.js +++ b/string-lerp.js @@ -92,41 +92,35 @@ return editPath(costMatrix(source, target, ins, del, sub), target); } - function patch(diff, source) { - /** Apply a list of edits to source */ - var edit; - var i; + function patchArray(diff, source) { + for (var i = 0; i < diff.length; ++i) { + var edit = diff[i]; + source.splice(edit[1], edit[0], edit[2]); + } + return source; + } - if (Array.isArray(source)) { - for (i = 0; i < diff.length; ++i) { - edit = diff[i]; - source.splice(edit[1], edit[0], edit[2]); - } - } else { - for (i = 0; i < diff.length; ++i) { - edit = diff[i]; - var head = source.slice(0, edit[1]); - var tail = source.slice(edit[1] + edit[0]); - source = head + edit[2] + tail; - } + function patchString(diff, source) { + for (var i = 0; i < diff.length; ++i) { + var edit = diff[i]; + var head = source.slice(0, edit[1]); + var tail = source.slice(edit[1] + edit[0]); + source = head + edit[2] + tail; } return source; } + function patch(diff, source) { + /** Apply a list of edits to source */ + var patcher = Array.isArray(source) ? patchArray : patchString; + return patcher(diff, source); + } + var MULTI = /[\uD800-\uDBFF][\uDC00-\uDFFF]|[\u0300-\u036F\u1DC0-\u1DFF\u20D0-\u20FF\uFE20-\uFE2F]/; var GLYPH = /([\0-\u02FF\u0370-\u1DBF\u1E00-\u20CF\u2100-\uD7FF\uDC00-\uFE1F\uFE30-\uFFFF]|[\uD800-\uDBFF][\uDC00-\uDFFF]|[\uD800-\uDBFF])([\u0300-\u036F\u1DC0-\u1DFF\u20D0-\u20FF\uFE20-\uFE2F]*)/g; - function diffLerp(source, target, amount ) { - /** Interpolate between two strings using edit operations - - This interpolation algorithm applys a partial edit of one - string into the other. This produces nice looking results, - but can take a significant amount of time and memory to - compute the edits. It is not recommended for strings - longer than a few hundred characters. - */ - + function diffLerpAstral(source, target, amount) { // If given strings with astral codepoints or combining // characters, split them into arrays of "glyphs" first, // do the edit on the list of "glyphs", and rejoin them. @@ -134,22 +128,44 @@ // This split is not perfect for all languages, but at least // it won't create invalid surrogate pairs or orphaned // combining characters. - if (source.match && (source.match(MULTI) || target.match(MULTI))) { - var sourceGlyphs = source.match(GLYPH) || []; - var targetGlyphs = target.match(GLYPH) || []; - return diffLerp(sourceGlyphs, targetGlyphs, amount).join(""); - } - + var sourceGlyphs = source.match(GLYPH) || []; + var targetGlyphs = target.match(GLYPH) || []; + var edits = diff(targetGlyphs, sourceGlyphs, 2, 2, 3); // The edit path works from the string end, forwards, because // that's how Levenshtein edits work. To match LTR reading // direction (and the behavior of fastLerp), swap the strings // and invert the parameter when editing. + var partial = edits.slice(0, Math.round((1 - amount) * edits.length)); + return patchArray(partial, targetGlyphs).join(""); + } + + function diffLerpBasic(source, target, amount) { var edits = diff(target, source, 2, 2, 3); + // The edit path works from the string end, forwards, because + // that's how Levenshtein edits work. To match LTR reading + // direction (and the behavior of fastLerp), swap the strings + // and invert the parameter when editing. var partial = edits.slice(0, Math.round((1 - amount) * edits.length)); - return patch(partial, target); + return patchString(partial, target); + } + + function diffLerp(source, target, amount) { + /** Interpolate between two strings using edit operations + + This interpolation algorithm applys a partial edit of one + string into the other. This produces nice looking results, + but can take a significant amount of time and memory to + compute the edits. It is not recommended for strings + longer than a few hundred characters. + */ + + if (source.match(MULTI) || target.match(MULTI)) + return diffLerpAstral(source, target, amount); + else + return diffLerpBasic(source, target, amount); } - var NUMBERS = /(-?\d+(?:\.\d+)?)/g; + var NUMBERS = /(-?\d{1,20}(?:\.\d{1,20})?)/g; function areNumericTwins(source, target) { /** Check if a and b differ only in numerals */ @@ -166,10 +182,10 @@ Numbers may have a leading "-" and a single "." to mark the decimal point, but something must be after the ".". No other floating point syntax (e.g. 1e6) is supported. - If both of the numbers in a pair are integers, the result - is clamped to an integer. + They are treated as fixed-point values, with the point's + position itself interpolating. - For example, numericLerp("0.0", "100", 0.123) === "12.3" + For example, numericLerp("0.0", "100".0, 0.123) === "12.3" because the "." in "0.0" is interpreted as a decimal point. But numericLerp("0.", "100.", 0.123) === "12." because the strings are interpreted as integers followed @@ -179,7 +195,6 @@ numerals gives undefined results. */ - // TODO: Try to preserve precision of the original numbers. var sourceParts = source.split(NUMBERS); var targetParts = target.split(NUMBERS); var destParts = targetParts; @@ -189,14 +204,35 @@ var part = nlerp(+sourcePart, +targetPart, amount); var sourcePoint = sourcePart.indexOf("."); var targetPoint = targetPart.indexOf("."); - if (sourcePoint === -1 && targetPoint === -1) - part = Math.round(part); - targetParts[i] = part.toString(); + var point = Math.round(nlerp( + sourcePoint >= 0 ? (sourcePart.length - 1) - sourcePoint : 0, + targetPoint >= 0 ? (targetPart.length - 1) - targetPoint : 0, + amount)); + targetParts[i] = part.toFixed(point); } return targetParts.join(""); } - function fastLerp(a, b, p) { + function fastLerpAstral(source, target, amount) { + var sourceGlyphs = source.match(GLYPH) || []; + var targetGlyphs = target.match(GLYPH) || []; + var sourceLength = Math.round(sourceGlyphs.length * amount); + var targetLength = Math.round(targetGlyphs.length * amount); + var head = targetGlyphs.slice(0, targetLength); + var tail = sourceGlyphs.slice(sourceLength, sourceGlyphs.length); + head.push.apply(head, tail); + return head.join(""); + } + + function fastLerpBasic(source, target, amount) { + var sourceLength = Math.round(source.length * amount); + var targetLength = Math.round(target.length * amount); + var head = target.substring(0, targetLength); + var tail = source.substring(sourceLength, source.length); + return head + tail; + } + + function fastLerp(source, target, amount) { /** Interpolate between two strings based on length This interpolation algorithm progressively replaces the @@ -208,22 +244,13 @@ // strings, e.g. in the megabyte range. These are large enough // that it should be fine to just pick a codepoint and search // for the nearest glyph start. - if (a.match(MULTI) || b.match(MULTI)) { - var ca = a.match(GLYPH) || []; - var cb = b.match(GLYPH) || []; - var calen = Math.round(ca.length * p); - var cblen = Math.round(cb.length * p); - var r = cb.slice(0, cblen); - r.push.apply(r, ca.slice(calen, ca.length)); - return r.join(""); - } else { - var alen = Math.round(a.length * p); - var blen = Math.round(b.length * p); - return b.substring(0, blen) + a.substring(alen, a.length); - } + if (source.match(MULTI) || target.match(MULTI)) + return fastLerpAstral(source, target, amount); + else + return fastLerpBasic(source, target, amount); } - function lerp(a, b, p) { + function lerp(source, target, amount) { /** Interpolate between two strings as best as possible If the strings are identical aside from numbers in them, @@ -234,23 +261,24 @@ Otherwise, they are passed through fastLerp. */ - a = a.toString(); - b = b.toString(); + source = source.toString(); + target = target.toString(); // Fast path for boundary cases. - if (p === 0) return a; - if (p === 1) return b; + if (amount === 0) return source; + if (amount === 1) return target; - if (areNumericTwins(a, b)) - return numericLerp(a, b, p); + if (areNumericTwins(source, target)) + return numericLerp(source, target, amount); // Numeric lerps should over- and under-shoot when fed numbers // outside 0 to 1, but other types cannot. - if (p < 0) return a; - if (p > 1) return b; + if (amount < 0) return source; + if (amount > 1) return target; - var n = a.length * b.length; - return ((n && n < MAX_MATRIX_SIZE) ? diffLerp : fastLerp)(a, b, p); + var n = source.length * target.length; + var appropriate = (n && n < MAX_MATRIX_SIZE) ? diffLerp : fastLerp; + return appropriate(source, target, amount); } exports.costMatrix = costMatrix;