[FIX] index exceeding bounds edge cases. [TESTS] all cases.

compute-io · Mar 3, 2015 · 1c9cab4 · 1c9cab4
1 parent d188c63
commit 1c9cab4
Show file tree

Hide file tree

Showing 3 changed files with 146 additions and 20 deletions.
diff --git a/README.md b/README.md
@@ -81,7 +81,7 @@ This implementation chooses to follow the Python convention such that `[:n]` com
 var indexspace = require( 'compute-indexspace' );
 
 var arr = indexspace( '[:]', 5 );
-// returns [ 1, 2, 3, 4 ]; 
+// returns [ 0, 1, 2, 3, 4 ] 
 
 arr = indexspace( '[2:]', 5 );
 // returns [ 2, 3, 4 ]

diff --git a/lib/index.js b/lib/index.js
@@ -92,8 +92,7 @@ var re = /^\[(?:(?:-(?=\d+))?\d*|end(?:-\d+|\/\d+)?):(?:(?:-(?=\d+))?\d*|end(?:-
 */
 
 var reEnd = /^end/,
-	reMatch = /(-|\/)(?=\d+)(\d+)?$/,
-	reDigit = /(-?\d+)/;
+	reMatch = /(-|\/)(?=\d+)(\d+)?$/;
 
 
 // INDEXSPACE
@@ -122,21 +121,11 @@ function indexspace( str, len ) {
 		return [];
 	}
 	str = str.split( ':' );
-
-	tmp = str[ 0 ].match( reDigit );
-	if ( tmp ) {
-		x1 = parseInt( tmp[ 1 ], 10 );
-	} else {
-		x1 = NaN;
-	}
-	tmp = str[ 1 ].match( reDigit );
-	if ( tmp ) {
-		x2 = parseInt( tmp[ 1 ], 10 );
-	} else {
-		x2 = NaN;
-	}
+	x1 = str[ 0 ].substr( 1 );
+	x2 = str[ 1 ];
 
 	if ( str.length === 2 ) {
+		x2 = x2.substr( 0, x2.length-1 );
 		inc = 1;
 	} else {
 		inc = parseInt( str[ 2 ], 10 );
@@ -166,6 +155,8 @@ function indexspace( str, len ) {
 			x1 = len - 1;
 		}
 	} else {
+		x1 = parseInt( x1, 10 );
+
 		// Handle empty index...
 		if ( x1 !== x1 ) {
 			// [:-?\d*:-?\d+]
@@ -185,6 +176,10 @@ function indexspace( str, len ) {
 				x1 = 0;
 			}
 		}
+		// Handle exceeding bounds...
+		else if ( x1 >= len ) {
+			return [];
+		}
 	}
 
 	// END //
@@ -201,12 +196,14 @@ function indexspace( str, len ) {
 				}
 			} else {
 				x2 = (len-1) / parseInt( tmp[ 2 ], 10 );
-				x2 = Math.floor( x2 );
+				x2 = Math.ceil( x2 ) - 1;
 			}
 		} else {
 			x2 = len - 1;
 		}
 	} else {
+		x2 = parseInt( x2, 10 );
+
 		// Handle empty index...
 		if ( x2 !== x2 ) {
 			// [-?\d*::-?\d+]
@@ -230,7 +227,11 @@ function indexspace( str, len ) {
 		else {
 			if ( inc < 0 ) {
 				x2 = x2 + 1;
-			} else {
+			}
+			else if ( x2 >= len ) {
+				x2 = len - 1;
+			}
+			else {
 				x2 = x2 - 1;
 			}
 		}
@@ -244,7 +245,6 @@ function indexspace( str, len ) {
 	if ( x1 === x2 ) {
 		return arr;
 	}
-	// Handle empty cases...
 	if ( inc < 0 ) {
 		if ( x2 > x1 ) {
 			return arr;

diff --git a/test/test.js b/test/test.js
@@ -88,7 +88,99 @@ describe( 'compute-indexspace', function tests() {
 	});
 
 	it( 'should return an index array', function test() {
+		var actual, expected;
 
+		actual = indexspace( '[:]', 5 );
+		expected = [ 0, 1, 2, 3, 4 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[2:]', 5 );
+		expected = [ 2, 3, 4 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[:3]', 5 );
+		expected = [ 0, 1, 2 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[2:4]', 5 );
+		expected = [ 2, 3 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[1:4:2]', 5 );
+		expected = [ 1, 3 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[2::2]', 5 );
+		expected = [ 2, 4 ];
+		assert.deepEqual( actual, expected );
+
+		actual =  indexspace( '[:10:3]', 20 );
+		expected = [ 0, 3, 6, 9 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[:-1:2]', 5 );
+		expected = [ 0, 2 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[-4:-1:2]', 5 );
+		expected = [ 0, 2 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[-5:-1]', 5 );
+		expected = [ 0, 1, 2, 3 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[::-1]', 5 );
+		expected = [ 4, 3, 2, 1, 0 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[:0:-1]', 5 );
+		expected = [ 4, 3, 2, 1 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[3:0:-1]', 5 );
+		expected = [ 3, 2, 1 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[-1:-4:-2]', 5 );
+		expected = [ 3, 1 ];
+		assert.deepEqual( actual, expected );
+	});
+
+	it( 'should support an `end` keyword', function test() {
+		var actual, expected;
+
+		actual = indexspace( '[:end]', 5 );
+		expected = [ 0, 1, 2, 3, 4 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[end::-1]', 5 );
+		expected = [ 4, 3, 2, 1, 0 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[:end-1]', 5 );
+		expected = [ 0, 1, 2, 3 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[:end/2]', 5 );
+		expected = [ 0, 1 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[:end/2]', 6 );
+		expected = [ 0, 1, 2 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[end-2::-1]', 5 );
+		expected = [ 2, 1, 0 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[end/2:]', 5 );
+		expected = [ 2, 3, 4 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[end/2:]', 6 );
+		expected = [ 3, 4, 5 ];
+		assert.deepEqual( actual, expected );
 	});
 
 	it( 'should return an empty array if provided a reference array length equal to 0', function test() {
@@ -97,7 +189,12 @@ describe( 'compute-indexspace', function tests() {
 	});
 
 	it( 'should return an empty array if start and end indices are equal', function test() {
-		var actual = indexspace( '[2:2]', 10 );
+		var actual;
+
+		actual = indexspace( '[2:]', 3 );
+		assert.deepEqual( actual, [] );
+
+		actual = indexspace( '[:2:-1]', 3 );
 		assert.deepEqual( actual, [] );
 	});
 
@@ -111,4 +208,33 @@ describe( 'compute-indexspace', function tests() {
 		assert.deepEqual( actual, [] );
 	});
 
+	it( 'should return an empty array if start index is greater than maximum index', function test() {
+		var actual = indexspace( '[5:]', 5 );
+		assert.deepEqual( actual, [] );
+	});
+
+	it( 'should be forgiving if the user exceeds index bounds', function test() {
+		var actual, expected;
+
+		actual = indexspace( '[-10:]', 5 );
+		expected = [ 0, 1, 2, 3, 4 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[:10]', 5 );
+		expected = [ 0, 1, 2, 3, 4 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[:-10:-1]', 5 );
+		expected = [ 4, 3, 2, 1, 0 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[end-10:]', 5 );
+		expected = [ 0, 1, 2, 3, 4 ];
+		assert.deepEqual( actual, expected );
+
+		actual = indexspace( '[:end-10:-1]', 5 );
+		expected = [ 4, 3, 2, 1, 0 ];
+		assert.deepEqual( actual, expected );
+	});
+
 });