Checkin of C string stuff. Fix several bugs, including most escape codes being

printed as '\\n' instead of their correct code.  Also print things in octal instead of hex.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1022 91177308-0d34-0410-b5e6-96231b3b80d8

support/lib/Support/StringExtras.cpp

@@ -0,0 +1,66 @@
+
+
+#include "llvm/Support/StringExtras.h"
+#include "llvm/ConstPoolVals.h"
+#include "llvm/DerivedTypes.h"
+
+// Can we treat the specified array as a string?  Only if it is an array of
+// ubytes or non-negative sbytes.
+//
+bool isStringCompatible(ConstPoolArray *CPA) {
+  const Type *ETy = cast<ArrayType>(CPA->getType())->getElementType();
+  if (ETy == Type::UByteTy) return true;
+  if (ETy != Type::SByteTy) return false;
+
+  for (unsigned i = 0; i < CPA->getNumOperands(); ++i)
+    if (cast<ConstPoolSInt>(CPA->getOperand(i))->getValue() < 0)
+      return false;
+
+  return true;
+}
+
+// toOctal - Convert the low order bits of X into an octal letter
+static inline char toOctal(int X) {
+  return (X&7)+'0';
+}
+
+// getAsCString - Return the specified array as a C compatible string, only if
+// the predicate isStringCompatible is true.
+//
+string getAsCString(ConstPoolArray *CPA) {
+  if (isStringCompatible(CPA)) {
+    string Result;
+    const Type *ETy = cast<ArrayType>(CPA->getType())->getElementType();
+    Result = "\"";
+    for (unsigned i = 0; i < CPA->getNumOperands(); ++i) {
+      unsigned char C = (ETy == Type::SByteTy) ?
+        (unsigned char)cast<ConstPoolSInt>(CPA->getOperand(i))->getValue() :
+        (unsigned char)cast<ConstPoolUInt>(CPA->getOperand(i))->getValue();
+
+      if (isprint(C)) {
+        Result += C;
+      } else {
+        switch(C) {
+        case '\a': Result += "\\a"; break;
+        case '\b': Result += "\\b"; break;
+        case '\f': Result += "\\f"; break;
+        case '\n': Result += "\\n"; break;
+        case '\r': Result += "\\r"; break;
+        case '\t': Result += "\\t"; break;
+        case '\v': Result += "\\v"; break;
+        default:
+          Result += '\\';
+          Result += toOctal(C >> 6);
+          Result += toOctal(C >> 3);
+          Result += toOctal(C >> 0);
+          break;
+        }
+      }
+    }
+    Result += "\"";
+
+    return Result;
+  } else {
+    return CPA->getStrValue();
+  }
+}