Data commit

Task/Palindrome-detection/D/palindrome-detection-1.d

@@ -0,0 +1,22 @@
+import std.traits, std.algorithm;
+
+bool isPalindrome1(C)(in C[] s) pure /*nothrow*/
+if (isSomeChar!C) {
+    auto s2 = s.dup;
+    s2.reverse(); // works on Unicode too, not nothrow.
+    return s == s2;
+}
+
+void main() {
+    alias pali = isPalindrome1;
+    assert(pali(""));
+    assert(pali("z"));
+    assert(pali("aha"));
+    assert(pali("sees"));
+    assert(!pali("oofoe"));
+    assert(pali("deified"));
+    assert(!pali("Deified"));
+    assert(pali("amanaplanacanalpanama"));
+    assert(pali("ingirumimusnocteetconsumimurigni"));
+    assert(pali("salàlas"));
+}

Task/Palindrome-detection/D/palindrome-detection-2.d

@@ -0,0 +1,26 @@
+import std.traits;
+
+bool isPalindrome2(C)(in C[] s) pure if (isSomeChar!C) {
+    dchar[] dstr;
+    foreach (dchar c; s) // not nothrow
+        dstr ~= c;
+
+    for (int i; i < dstr.length / 2; i++)
+        if (dstr[i] != dstr[$ - i - 1])
+            return false;
+    return true;
+}
+
+void main() {
+    alias isPalindrome2 pali;
+    assert(pali(""));
+    assert(pali("z"));
+    assert(pali("aha"));
+    assert(pali("sees"));
+    assert(!pali("oofoe"));
+    assert(pali("deified"));
+    assert(!pali("Deified"));
+    assert(pali("amanaplanacanalpanama"));
+    assert(pali("ingirumimusnocteetconsumimurigni"));
+    assert(pali("salàlas"));
+}

Task/Palindrome-detection/D/palindrome-detection-3.d

@@ -0,0 +1,39 @@
+import std.stdio, core.exception, std.traits;
+
+// assume alloca() to be pure for this program
+extern(C) pure nothrow void* alloca(in size_t size);
+
+bool isPalindrome3(C)(in C[] s) pure if (isSomeChar!C) {
+    auto p = cast(dchar*)alloca(s.length * 4);
+    if (p == null)
+        // no fallback heap allocation used
+        throw new OutOfMemoryError();
+    dchar[] dstr = p[0 .. s.length];
+
+    // use std.utf.stride for an even lower level version
+    int i = 0;
+    foreach (dchar c; s) { // not nothrow
+        dstr[i] = c;
+        i++;
+    }
+    dstr = dstr[0 .. i];
+
+    foreach (j; 0 .. dstr.length / 2)
+        if (dstr[j] != dstr[$ - j - 1])
+            return false;
+    return true;
+}
+
+void main() {
+    alias isPalindrome3 pali;
+    assert(pali(""));
+    assert(pali("z"));
+    assert(pali("aha"));
+    assert(pali("sees"));
+    assert(!pali("oofoe"));
+    assert(pali("deified"));
+    assert(!pali("Deified"));
+    assert(pali("amanaplanacanalpanama"));
+    assert(pali("ingirumimusnocteetconsumimurigni"));
+    assert(pali("salàlas"));
+}

Task/Palindrome-detection/D/palindrome-detection-4.d

@@ -0,0 +1,23 @@
+bool isPalindrome4(in string str) pure nothrow {
+    if (str.length == 0) return true;
+    immutable(char)* s = str.ptr;
+    immutable(char)* t = &(str[$ - 1]);
+    while (s < t)
+        if (*s++ != *t--) // ugly
+            return false;
+    return true;
+}
+
+void main() {
+    alias isPalindrome4 pali;
+    assert(pali(""));
+    assert(pali("z"));
+    assert(pali("aha"));
+    assert(pali("sees"));
+    assert(!pali("oofoe"));
+    assert(pali("deified"));
+    assert(!pali("Deified"));
+    assert(pali("amanaplanacanalpanama"));
+    assert(pali("ingirumimusnocteetconsumimurigni"));
+    //assert(pali("salàlas"));
+}