From e183a128858719f968a20bf84c8780a362316422 Mon Sep 17 00:00:00 2001
From: arphaman <arphaman@gmail.com>
Date: Wed, 18 Sep 2013 14:35:17 +0100
Subject: added support for INDEX intrinsic

---
 include/Strings/Character.h |  5 +++++
 lib/Strings/Character.cpp   | 52 +++++++++++++++++++++++++++++++++++++++++++++
 test/Unit/CMakeLists.txt    |  1 +
 test/Unit/index.cpp         | 49 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 107 insertions(+)
 create mode 100644 test/Unit/index.cpp

diff --git a/include/Strings/Character.h b/include/Strings/Character.h
index 134d901..bbaf70c 100644
--- a/include/Strings/Character.h
+++ b/include/Strings/Character.h
@@ -26,6 +26,11 @@ LIBFLANG_ABI int32_t libflang_compare_char1(const char *LHS, size_t LHSLength,
 
 LIBFLANG_ABI int32_t libflang_lexcompare_char1(const char *LHS, size_t LHSLength,
                                                const char *RHS, size_t RHSLength);
+
+LIBFLANG_ABI size_t libflang_index_char1(const char *String, size_t Length,
+                                         const char *SubString, size_t SubLength,
+                                         int32_t Back);
+
 LIBFLANG_ABI size_t libflang_lentrim_char1(const char *String, size_t Length);
 
 #endif
diff --git a/lib/Strings/Character.cpp b/lib/Strings/Character.cpp
index e5274bf..823f8e3 100644
--- a/lib/Strings/Character.cpp
+++ b/lib/Strings/Character.cpp
@@ -14,6 +14,10 @@ struct CharacterValue {
   CharacterValue<T> sliceFrom(size_t Start) const {
     return CharacterValue<T>(Ptr + Start, Length - Start);
   }
+
+  T operator[] (size_t I) const {
+    return Ptr[I];
+  }
 };
 
 static inline
@@ -81,6 +85,47 @@ static int32_t lexcompare(const CharacterValue<T> LHS,
   return 0;//FIXME
 }
 
+template<typename T>
+static size_t index(const CharacterValue<T> String,
+                    const CharacterValue<T> SubString) {
+  if(String.Length < SubString.Length)
+    return 0;
+  if(!SubString.Length) return 1;
+
+  auto Range = String.Length - SubString.Length;
+  for(size_t I = 0; I <= Range; ++I) {
+    bool Match = true;
+    for(size_t J = 0; J < SubString.Length; ++J) {
+      if(String[I+J] != SubString[J]) {
+        Match = false;
+        break;
+      }
+    }
+    if(Match) return I+1;
+  }
+  return 0;
+}
+
+template<typename T>
+static size_t index_reverse(const CharacterValue<T> String,
+                            const CharacterValue<T> SubString) {
+  if(String.Length < SubString.Length)
+    return 0;
+  if(!SubString.Length) return String.Length + 1;
+
+  for(size_t I = String.Length - SubString.Length + 1; I != 0; --I) {
+    bool Match = true;
+    for(size_t J = 0; J < SubString.Length; ++J) {
+      if(String[I-1+J] != SubString[J]) {
+        Match = false;
+        break;
+      }
+    }
+    if(Match) return I;
+  }
+  return 0;
+}
+
 template<typename T>
 static size_t lentrim(const CharacterValue<T> String) {
   for(size_t I = String.Length; I > 0; I--) {
@@ -115,6 +160,13 @@ LIBFLANG_ABI int32_t libflang_lexcompare_char1(const char *LHS, size_t LHSLength
   return lexcompare(generic(LHS, LHSLength), generic(RHS, RHSLength));
 }
 
+LIBFLANG_ABI size_t libflang_index_char1(const char *String, size_t Length,
+                                         const char *SubString, size_t SubLength,
+                                         int32_t Back) {
+  return Back == 0? index(generic(String, Length), generic(SubString, SubLength)) :
+                    index_reverse(generic(String, Length), generic(SubString, SubLength));
+}
+
 LIBFLANG_ABI size_t libflang_lentrim_char1(const char *String, size_t Length) {
   return lentrim(generic(String, Length));
 }
diff --git a/test/Unit/CMakeLists.txt b/test/Unit/CMakeLists.txt
index 0b648ef..af1eaa6 100644
--- a/test/Unit/CMakeLists.txt
+++ b/test/Unit/CMakeLists.txt
@@ -1,2 +1,3 @@
 add_libflang_test(ipow ipow.cpp)
 add_libflang_test(selected_int_kind selected_int_kind.cpp)
+add_libflang_test(index index.cpp)
diff --git a/test/Unit/index.cpp b/test/Unit/index.cpp
new file mode 100644
index 0000000..ed5107b
--- /dev/null
+++ b/test/Unit/index.cpp
@@ -0,0 +1,49 @@
+//===-- index.cpp - Test libflang_index_char* -----------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include <assert.h>
+#include <string.h>
+#include <iostream>
+#include "Strings/Character.h"
+
+static bool testIndex(const char *str, const char *substr, size_t expected, bool back = false) {
+  auto x = libflang_index_char1(str, strlen(str), substr, strlen(substr),
+                                back? 1:0);
+  if(x != expected)
+    std::cout << "Error in libflang_index - expected " << expected
+              << ", got " << x << std::endl;
+  return x != expected;
+}
+
+int main() {
+  if(testIndex("FORTRAN","R",3))
+    return 1;
+  if(testIndex("FORTRAN","R",5,true))
+    return 1;
+  if(testIndex("hello","ell",2))
+    return 1;
+  if(testIndex("hello","ell",2,true))
+    return 1;
+  if(testIndex("hello","world",0))
+    return 1;
+  if(testIndex("hello","world",0,true))
+    return 1;
+  if(testIndex("A","a",0))
+    return 1;
+  if(testIndex("hell","hello",0))
+    return 1;
+  if(testIndex("hell","hello",0,true))
+    return 1;
+  if(testIndex("hello","",1))
+    return 1;
+  if(testIndex("hello","",6,true))
+    return 1;
+  return 0;
+}
+
-- 
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