Dart version of double.parse that works for numbers that can be represented

tests/corelib/double_parse_test.dart

+// Copyright (c) 2014 the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "dart:math" show pow;
+import "package:expect/expect.dart";
+
+const whiteSpace = const [
+  "",
+  "\x09",
+  "\x0a",
+  "\x0b",
+  "\x0c",
+  "\x0d",
+  "\x85",    /// 01: ok
+  "\xa0",
+  "\u1680",
+  "\u180e",
+  "\u2000",
+  "\u2001",
+  "\u2002",
+  "\u2003",
+  "\u2004",
+  "\u2005",
+  "\u2006",
+  "\u2007",
+  "\u2008",
+  "\u2009",
+  "\u200a",
+  "\u2028",
+  "\u2029",
+  "\u202f",
+  "\u205f",
+  "\u3000",
+  "\uFEFF"
+];
+
+void expectNumEquals(double expect, var actual, String message) {
+  if (expect.isNaN) {
+    Expect.isTrue(actual is double && actual.isNaN, "isNaN: $message");
+  } else {
+    Expect.identical(expect, actual, message);
+  }
+}
+
+// Test source surrounded by any combination of whitespace.
+void testParseAllWhitespace(String source, double result) {
+  for (String ws1 in whiteSpace) {
+    for (String ws2 in whiteSpace) {
+      String padded = "$ws1$source$ws2";
+      // Use Expect.identical because it also handles NaN and 0.0/-0.0.
+      // Except on dart2js: http://dartbug.com/11551
+      expectNumEquals(result, double.parse(padded), "parse '$padded'");
+      padded = "$ws1$ws2$source";
+      expectNumEquals(result, double.parse(padded), "parse '$padded'");
+      padded = "$source$ws1$ws2";
+      expectNumEquals(result, double.parse(padded), "parse '$padded'");
+    }
+  }
+}
+
+// Test source and -source surrounded by any combination of whitespace.
+void testParseWhitespace(String source, double result) {
+  assert(result >= 0);
+  testParseAllWhitespace(source, result);
+  testParseAllWhitespace("-$source", -result);
+}
+
+// Test parsing source, optionally preceeded and/or followed by whitespace.
+void testParse(String source, double result, [name = ""]) {
+  expectNumEquals(result, double.parse(source), "parse '$source:$name");
+  expectNumEquals(result, double.parse(" $source"),
+                  "parse ' $source':$name");
+  expectNumEquals(result, double.parse("$source "),
+                  "parse '$source ':$name");
+  expectNumEquals(result, double.parse(" $source "),
+                  "parse ' $source ':$name");
+
+  expectNumEquals(result, double.parse("+$source"),
+                  "parse '+$source:$name");
+  expectNumEquals(result, double.parse(" +$source"),
+                  "parse ' +$source':$name");
+  expectNumEquals(result, double.parse("+$source "),
+                  "parse '+$source ':$name");
+  expectNumEquals(result, double.parse(" +$source "),
+                  "parse ' +$source ':$name");
+
+  expectNumEquals(-result, double.parse("-$source"),
+                  "parse '-$source:$name");
+  expectNumEquals(-result, double.parse(" -$source"),
+                  "parse ' -$source':$name");
+  expectNumEquals(-result, double.parse("-$source "),
+                  "parse '-$source ':$name");
+  expectNumEquals(-result, double.parse(" -$source "),
+                  "parse ' -$source ':$name");
+}
+
+void testDouble(double value) {
+  testParse("$value", value);
+  if (value.isFinite) {
+    String exp = value.toStringAsExponential();
+    String lcexp = exp.toLowerCase();
+    testParse(lcexp, value);
+    String ucexp = exp.toUpperCase();
+    testParse(ucexp, value);
+  }
+}
+
+void testFail(String source) {
+  var object = new Object();
+  Expect.throws(() {
+    double.parse(source, (s) {
+      Expect.equals(source, s);
+      throw object;
+    });
+  }, (e) => identical(object, e), "Fail: '$source'");
+}
+
+void main() {
+  testDouble(0.0);
+  testDouble(5e-324);
+  testDouble(2.225073858507201e-308);
+  testDouble(2.2250738585072014e-308);
+  testDouble(0.49999999999999994);
+  testDouble(0.5);
+  testDouble(0.50000000000000006);
+  testDouble(0.9999999999999999);
+  testDouble(1.0);
+  testDouble(1.0000000000000002);
+  testDouble(4294967295.0);
+  testDouble(4294967296.0);
+  testDouble(4503599627370495.5);
+  testDouble(4503599627370497.0);
+  testDouble(9007199254740991.0);
+  testDouble(9007199254740992.0);
+  testDouble(1.7976931348623157e+308);
+  testDouble(double.INFINITY);
+  testDouble(double.NAN);
+
+  // Strings that cannot occur from toString of a number.
+  testParse("000000000000", 0.0);
+  testParse("000000000001", 1.0);
+  testParse("000000000000.0000000000000", 0.0);
+  testParse("000000000001.0000000000000", 1.0);
+  testParse("0e0", 0.0);
+  testParse("0e+0", 0.0);
+  testParse("0e-0", 0.0);
+  testParse("1e0", 1.0);
+  testParse("1e+0", 1.0);
+  testParse("1e-0", 1.0);
+  testParse("1.", 1.0);
+  testParse(".1", 0.1);
+  testParse("1.e1", 10.0);
+  testParse(".1e1", 1.0);
+  testParse("Infinity", double.INFINITY);
+  testParse("NaN", double.NAN);
+
+  // Cases where mantissa and 10^exponent are representable as a double.
+  for (int i = -22; i <= 22; i++) {
+    for (double j in [1.0, 9007199254740991.0, 9007199254740992.0]) {
+      var value = (i >= 0) ? j * pow(10.0, i) : j / pow(10.0, -i);
+      testParse("${j}e$i", value, "$i/$j");
+      testParse("${j}E$i", value, "$i/$j");
+      if (i >= 0) {
+        testParse("${j}e+$i", value, "$i/$j");
+        testParse("${j}E+$i", value, "$i/$j");
+      }
+    }
+  }
+  for (int i = 0; i <= 22; i++) {
+    var digits = "9007199254740991";
+    for (int i = 0; i < digits.length; i++) {
+      int dotIndex = digits.length - i;
+      var string = "${digits.substring(0, dotIndex)}."
+                   "${digits.substring(dotIndex)}e$i";
+      testParse(string, 9007199254740991.0);
+    }
+  }
+
+  testParse("9007199254740993", 9007199254740992.0);
+  testParse("9.007199254740993e15", 9007199254740992.0);
+  testParse("0.00000009007199254740991e23", 9007199254740991.0);
+
+  testParse("0.000000000000000000000000000000000000000000000000"
+            "00000000000000000000000000000000000000000000000000"
+            "00000000000000000000000000000000000000000000000000"
+            "00000000000000000000000000000000000000000000000000"
+            "00000000000000000000000000000000000000000000000000"
+            "00000000000000000000000000000000000000000000000000"
+            "00000000000000000000000004940656458412465441765687"
+            "92868221372365059802614324764425585682500675507270"
+            "20875186529983636163599237979656469544571773092665"
+            "67103559397963987747960107818781263007131903114045"
+            "27845817167848982103688718636056998730723050006387"
+            "40915356498438731247339727316961514003171538539807"
+            "41262385655911710266585566867681870395603106249319"
+            "45271591492455329305456544401127480129709999541931"
+            "98940908041656332452475714786901472678015935523861"
+            "15501348035264934720193790268107107491703332226844"
+            "75333572083243193609238289345836806010601150616980"
+            "97530783422773183292479049825247307763759272478746"
+            "56084778203734469699533647017972677717585125660551"
+            "19913150489110145103786273816725095583738973359899"
+            "36648099411642057026370902792427675445652290875386"
+            "82506419718265533447265625", 5e-324);
+
+  testParse("0.000000000000000000000000000000000000000000000000"
+            "00000000000000000000000000000000000000000000000000"
+            "00000000000000000000000000000000000000000000000000"
+            "00000000000000000000000000000000000000000000000000"
+            "00000000000000000000000000000000000000000000000000"
+            "00000000000000000000000000000000000000000000000000"
+            "00000000000000000000000002470328229206232720882843"
+            "96434110686182529901307162382212792841250337753635"
+            "10437593264991818081799618989828234772285886546332"
+            "83551779698981993873980053909390631503565951557022"
+            "63922908583924491051844359318028499365361525003193"
+            "70457678249219365623669863658480757001585769269903"
+            "70631192827955855133292783433840935197801553124659"
+            "72635795746227664652728272200563740064854999770965"
+            "99470454020828166226237857393450736339007967761930"
+            "57750674017632467360096895134053553745851666113422"
+            "37666786041621596804619144672918403005300575308490"
+            "48765391711386591646239524912623653881879636239373"
+            "28042389101867234849766823508986338858792562830275"
+            "59956575244555072551893136908362547791869486679949"
+            "68324049705821028513185451396213837722826145437693"
+            "412532098591327667236328126", 5e-324);
+
+  testParse("0.000000000000000000000000000000000000000000000000"
+            "00000000000000000000000000000000000000000000000000"
+            "00000000000000000000000000000000000000000000000000"
+            "00000000000000000000000000000000000000000000000000"
+            "00000000000000000000000000000000000000000000000000"
+            "00000000000000000000000000000000000000000000000000"
+            "00000000000000000000000002470328229206232720882843"
+            "96434110686182529901307162382212792841250337753635"
+            "10437593264991818081799618989828234772285886546332"
+            "83551779698981993873980053909390631503565951557022"
+            "63922908583924491051844359318028499365361525003193"
+            "70457678249219365623669863658480757001585769269903"
+            "70631192827955855133292783433840935197801553124659"
+            "72635795746227664652728272200563740064854999770965"
+            "99470454020828166226237857393450736339007967761930"
+            "57750674017632467360096895134053553745851666113422"
+            "37666786041621596804619144672918403005300575308490"
+            "48765391711386591646239524912623653881879636239373"
+            "28042389101867234849766823508986338858792562830275"
+            "59956575244555072551893136908362547791869486679949"
+            "68324049705821028513185451396213837722826145437693"
+            "412532098591327667236328125", 0.0);
+
+  testParse("0.0000000000000000000000000000000000000000000000000"
+            "000000000000000000000000000000000000000000000000000"
+            "000000000000000000000000000000000000000000000000000"
+            "000000000000000000000000000000000000000000000000000"
+            "000000000000000000000000000000000000000000000000000"
+            "000000000000000000000000000000000000000000000000000"
+            "00022250738585072011", 2.225073858507201e-308);
+
+  testParse("0.0000000000000000000000000000000000000000000000000"
+            "000000000000000000000000000000000000000000000000000"
+            "000000000000000000000000000000000000000000000000000"
+            "000000000000000000000000000000000000000000000000000"
+            "000000000000000000000000000000000000000000000000000"
+            "000000000000000000000000000000000000000000000000000"
+            "00022250738585072012", 2.2250738585072014e-308);
+
+  testParse("0.49999999999999994", 0.49999999999999994);
+  testParse("0.49999999999999997219", 0.49999999999999994);
+  testParse("0.49999999999999999", 0.5);
+
+  testParseWhitespace("1", 1.0);
+  testParseWhitespace("1.0", 1.0);
+  testParseWhitespace("1e1", 10.0);
+  testParseWhitespace(".1e1", 1.0);
+  testParseWhitespace("1.e1", 10.0);
+  testParseWhitespace("1e+1", 10.0);
+  testParseWhitespace("1e-1", 0.1);
+
+  // Negative tests - things not to allow.
+
+  // Spaces inside the numeral.
+  testFail("- 1");
+  testFail("+ 1");
+  testFail("2 2");
+  testFail("1 .");
+  testFail(". 1");
+  testFail("1e 2");
+  testFail("1 e2");
+  // Invalid characters.
+  testFail("0x0");
+  testFail("0x1H");
+  testFail("12H");
+  testFail("1x2");
+  testFail("00x2");
+  testFail("0x2.2");
+  // Double exponent without value.
+  testFail(".e1");
+  testFail("e1");
+  testFail("e+1");
+  testFail("e-1");
+  testFail("-e1");
+  testFail("-e+1");
+  testFail("-e-1");
+  // Too many signs.
+  testFail("--1");
+  testFail("-+1");
+  testFail("+-1");
+  testFail("++1");
+  // Incorrect ways to write NaN/Infinity.
+  testFail("infinity");
+  testFail("INFINITY");
+  testFail("1.#INF");
+  testFail("inf");
+  testFail("nan");
+  testFail("NAN");
+  testFail("1.#IND");
+  testFail("indef");
+  testFail("qnan");
+  testFail("snan");
+}