| /* |
| Licensed to the Apache Software Foundation (ASF) under one or more |
| contributor license agreements. See the NOTICE file distributed with |
| this work for additional information regarding copyright ownership. |
| The ASF licenses this file to You under the Apache License, Version 2.0 |
| (the "License"); you may not use this file except in compliance with |
| the License. You may obtain a copy of the License at |
| |
| http://www.apache.org/licenses/LICENSE-2.0 |
| |
| Unless required by applicable law or agreed to in writing, software |
| distributed under the License is distributed on an "AS IS" BASIS, |
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| See the License for the specific language governing permissions and |
| limitations under the License. |
| */ |
| |
| /* |
| * A C function for R extension which implements the Java String hash algorithm. |
| * Refer to http://en.wikipedia.org/wiki/Java_hashCode%28%29#The_java.lang.String_hash_function |
| * |
| */ |
| |
| #include <R.h> |
| #include <Rinternals.h> |
| |
| /* for compatibility with R before 3.1 */ |
| #ifndef IS_SCALAR |
| #define IS_SCALAR(x, type) (TYPEOF(x) == (type) && XLENGTH(x) == 1) |
| #endif |
| |
| SEXP stringHashCode(SEXP string) { |
| const char* str; |
| R_xlen_t len, i; |
| int hashCode = 0; |
| |
| if (!IS_SCALAR(string, STRSXP)) { |
| error("invalid input"); |
| } |
| |
| str = CHAR(asChar(string)); |
| len = XLENGTH(asChar(string)); |
| |
| for (i = 0; i < len; i++) { |
| hashCode = (hashCode << 5) - hashCode + *str++; |
| } |
| |
| return ScalarInteger(hashCode); |
| } |