Added support for start-of-input (\A) and end-of-input (\Z) assertions

regex/compile.go

@@ -878,6 +878,10 @@ func thompson(re []postfixNode) (Reg, error) {
 						stateToAdd.assert = wboundAssert
 					case 'B':
 						stateToAdd.assert = nonwboundAssert
+					case 'A':
+						stateToAdd.assert = soiAssert
+					case 'Z':
+						stateToAdd.assert = eoiAssert
 					}
 				} else { // Lookaround
 					stateToAdd.lookaroundRegex = string(c.contents)