[[ LCB StdLib ]] Added syntax to convert codepoint indicies to chars.

runrevmark · runrevmark · commit 036699acfb30 · 2015-03-04T16:53:17.000Z
There are two new pieces of syntax:

    the code of &lt;string&gt;
    the char with code &lt;integer&gt;

These allow you to create a code point from an integer index, and to fetch the integer index of a given code point.
diff --git a/libscript/src/module-string.cpp b/libscript/src/module-string.cpp
@@ -114,6 +114,49 @@ extern "C" MC_DLLEXPORT void MCStringEvalIsGreaterThan(MCStringRef p_left, MCStr
     r_result = MCStringCompareTo(p_left, p_right, kMCStringOptionCompareExact) > 0;
 }
 
+extern "C" MC_DLLEXPORT void MCStringEvalCodeOfChar(MCStringRef p_string, uinteger_t& r_code)
+{
+    uindex_t t_length;
+    t_length = MCStringGetLength(p_string);
+    if (t_length == 0 || t_length > 2)
+        goto notacodepoint_exit;
+    
+    codepoint_t t_code;
+    t_code = MCStringGetCodepointAtIndex(p_string, 0);
+    if (t_length > 1 &&
+        t_code < 65536)
+        goto notacodepoint_exit;
+    
+    r_code = t_code;
+    
+    return;
+    
+notacodepoint_exit:
+    MCErrorThrowGeneric(MCSTR("not a single code character"));
+}
+
+extern "C" MC_DLLEXPORT void MCStringEvalCharWithCode(uinteger_t p_code, MCStringRef& r_string)
+{
+    if (p_code >= 1 << 21)
+    {
+        MCErrorThrowGeneric(MCSTR("code out of range"));
+        return;
+    }
+    
+    if (p_code >= 1 << 16)
+    {
+        unichar_t t_codeunits[2];
+        t_codeunits[0] =  unichar_t((p_code - 0x10000) >> 10) + 0xD800;
+        t_codeunits[1] = unichar_t((p_code - 0x10000) & 0x3FF) + 0xDC00;
+        MCStringCreateWithChars(t_codeunits, 2, r_string);
+        return;
+    }
+    
+    unichar_t t_codeunit;
+    t_codeunit = (unichar_t)p_code;
+    MCStringCreateWithChars(&t_codeunit, 1, r_string);
+}
+
 extern "C" MC_DLLEXPORT void MCStringEvalEmpty(MCStringRef& r_output)
 {
     r_output = MCValueRetain(kMCEmptyString);
diff --git a/libscript/src/string.mlc b/libscript/src/string.mlc
@@ -53,6 +53,9 @@ public foreign handler MCStringEvalIsGreaterThan(in Left as string, in Right as
 
 public foreign handler MCStringEvalEmpty(out Value as string) as undefined binds to "<builtin>"
 
+public foreign handler MCStringEvalCodeOfChar(in pChar as string, out pCode as uint) as undefined binds to "<builtin>"
+public foreign handler MCStringEvalCharWithCode(in pCode as uint, out pChar as string) as undefined binds to "<builtin>"
+
 --
 
 /*
@@ -307,6 +310,20 @@ end syntax
 
 --
 
+syntax CodeOfChar is prefix operator with precedence 2
+    "the" "code" "of" <Target: Expression>
+begin
+    MCStringEvalCodeOfChar(Target, output)
+end syntax
+
+syntax CharWithCode is prefix operator with precedence 2
+    "the" "char" "with" "code" <Index: Expression>
+begin
+    MCStringEvalCharWithCode(Index, output)
+end syntax
+
+--
+
 /* 
 
 Summary: 		Designates the string of length zero.
