87 lines
1.9 KiB
JavaScript
87 lines
1.9 KiB
JavaScript
/*
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MIT License http://www.opensource.org/licenses/mit-license.php
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Author Mikola Lysenko @mikolalysenko
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*/
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"use strict";
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/* cspell:disable-next-line */
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// Refactor: Peter Somogyvari @petermetz
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const compileSearch = (funcName, predicate, reversed, extraArgs, earlyOut) => {
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const code = [
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"function ",
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funcName,
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"(a,l,h,",
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extraArgs.join(","),
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"){",
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earlyOut ? "" : "var i=",
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reversed ? "l-1" : "h+1",
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";while(l<=h){var m=(l+h)>>>1,x=a[m]"
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];
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if (earlyOut) {
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if (predicate.indexOf("c") < 0) {
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code.push(";if(x===y){return m}else if(x<=y){");
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} else {
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code.push(";var p=c(x,y);if(p===0){return m}else if(p<=0){");
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}
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} else {
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code.push(";if(", predicate, "){i=m;");
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}
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if (reversed) {
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code.push("l=m+1}else{h=m-1}");
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} else {
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code.push("h=m-1}else{l=m+1}");
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}
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code.push("}");
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if (earlyOut) {
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code.push("return -1};");
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} else {
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code.push("return i};");
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}
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return code.join("");
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};
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const compileBoundsSearch = (predicate, reversed, suffix, earlyOut) => {
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const arg1 = compileSearch(
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"A",
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"x" + predicate + "y",
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reversed,
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["y"],
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earlyOut
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);
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const arg2 = compileSearch(
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"P",
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"c(x,y)" + predicate + "0",
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reversed,
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["y", "c"],
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earlyOut
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);
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const fnHeader = "function dispatchBinarySearch";
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const fnBody =
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"(a,y,c,l,h){\
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if(typeof(c)==='function'){\
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return P(a,(l===void 0)?0:l|0,(h===void 0)?a.length-1:h|0,y,c)\
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}else{\
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return A(a,(c===void 0)?0:c|0,(l===void 0)?a.length-1:l|0,y)\
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}}\
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return dispatchBinarySearch";
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const fnArgList = [arg1, arg2, fnHeader, suffix, fnBody, suffix];
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const fnSource = fnArgList.join("");
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const result = new Function(fnSource);
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return result();
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};
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module.exports = {
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ge: compileBoundsSearch(">=", false, "GE"),
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gt: compileBoundsSearch(">", false, "GT"),
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lt: compileBoundsSearch("<", true, "LT"),
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le: compileBoundsSearch("<=", true, "LE"),
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eq: compileBoundsSearch("-", true, "EQ", true)
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};
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