std.format.formatUnsigned: refactor

dlang · Jul 4, 2015 · f4e37c3 · f4e37c3
1 parent 67a08f1
commit f4e37c3
Showing 1 changed file with 72 additions and 85 deletions.
diff --git a/std/format.d b/std/format.d
@@ -1489,9 +1489,8 @@ unittest
     assert(w.data == "1337");
 }
 
-private void formatIntegral(Writer, T, Char)(Writer w, const(T) val, ref FormatSpec!Char f, uint base, ulong mask)
+private void formatIntegral(Writer, T, Char)(Writer w, const(T) val, const ref FormatSpec!Char fs, uint base, ulong mask)
 {
-    FormatSpec!Char fs = f; // fs is copy for change its values.
     T arg = val;
 
     bool negative = (base == 10 && arg < 0);
@@ -1507,105 +1506,93 @@ private void formatIntegral(Writer, T, Char)(Writer w, const(T) val, ref FormatS
         formatUnsigned(w, (cast(ulong) arg) & mask, fs, base, negative);
 }
 
-private void formatUnsigned(Writer, T, Char)(Writer w, T arg, ref FormatSpec!Char fs, uint base, bool negative)
+private void formatUnsigned(Writer, T, Char)(Writer w, T arg, const ref FormatSpec!Char fs, uint base, bool negative)
 {
-    if (fs.precision == fs.UNSPECIFIED)
-    {
-        // default precision for integrals is 1
-        fs.precision = 1;
-    }
-    else
+    /* Write string:
+     *    leftpad prefix1 prefix2 zerofill digits rightpad
+     */
+
+    /* Convert arg to digits[].
+     * Note that 0 becomes an empty digits[]
+     */
+    char[64] buffer = void; // 64 bits in base 2 at most
+    char[] digits;
     {
-        // if a precision is specified, the '0' flag is ignored.
-        fs.flZero = false;
+        size_t i = buffer.length;
+        while (arg)
+        {
+            --i;
+            char c = cast(char) (arg % base);
+            arg /= base;
+            if (c < 10)
+                buffer[i] = cast(char)(c + '0');
+            else
+                buffer[i] = cast(char)(c + (fs.spec == 'x' ? 'a' - 10 : 'A' - 10));
+        }
+        digits = buffer[i .. $]; // got the digits without the sign
     }
 
-    char leftPad = void;
-    if (!fs.flDash && !fs.flZero)
-        leftPad = ' ';
-    else if (!fs.flDash && fs.flZero)
-        leftPad = '0';
-    else
-        leftPad = 0;
 
-    // figure out sign and continue in unsigned mode
-    char forcedPrefix = void;
-    if (fs.flPlus) forcedPrefix = '+';
-    else if (fs.flSpace) forcedPrefix = ' ';
-    else forcedPrefix = 0;
-    if (base != 10)
+    int precision = (fs.precision == fs.UNSPECIFIED) ? 1 : fs.precision;
+
+    char padChar = 0;
+    if (!fs.flDash)
     {
-        // non-10 bases are always unsigned
-        forcedPrefix = 0;
+        padChar = (fs.flZero && fs.precision == fs.UNSPECIFIED) ? '0' : ' ';
     }
-    else if (negative)
+
+    // Compute prefix1 and prefix2
+    char prefix1 = 0;
+    char prefix2 = 0;
+    if (base == 10)
     {
-        // argument is signed
-        forcedPrefix = '-';
+        if (negative)
+            prefix1 = '-';
+        else if (fs.flPlus)
+            prefix1 = '+';
+        else if (fs.flSpace)
+            prefix1 = ' ';
     }
-    // fill the digits
-    char[64] buffer; // 64 bits in base 2 at most
-    char[] digits;
+    else if (base == 16 && fs.flHash && digits.length)
     {
-        uint i = buffer.length;
-        auto n = arg;
-        do
-        {
-            --i;
-            buffer[i] = cast(char) (n % base);
-            n /= base;
-            if (buffer[i] < 10) buffer[i] += '0';
-            else buffer[i] += (fs.spec == 'x' ? 'a' : 'A') - 10;
-        } while (n);
-        digits = buffer[i .. $]; // got the digits without the sign
+        prefix1 = '0';
+        prefix2 = fs.spec == 'x' ? 'x' : 'X';
     }
     // adjust precision to print a '0' for octal if alternate format is on
-    if (base == 8 && fs.flHash
-        && (fs.precision <= digits.length)) // too low precision
-    {
-        //fs.precision = digits.length + (arg != 0);
-        forcedPrefix = '0';
-    }
-    // write left pad; write sign; write 0x or 0X; write digits;
-    //   write right pad
-    // Writing left pad
-    ptrdiff_t spacesToPrint =
-        fs.width // start with the minimum width
-        - digits.length  // take away digits to print
-        - (forcedPrefix != 0) // take away the sign if any
-        - (base == 16 && fs.flHash && arg ? 2 : 0); // 0x or 0X
-    const ptrdiff_t delta = fs.precision - digits.length;
-    if (delta > 0) spacesToPrint -= delta;
+    else if (base == 8 && fs.flHash &&
+             (precision <= 1 || precision <= digits.length)) // too low precision
+        prefix1 = '0';
+
+    size_t zerofill = precision > digits.length ? precision - digits.length : 0;
+    size_t leftpad = 0;
+    size_t rightpad = 0;
+
+    ptrdiff_t spacesToPrint = fs.width - ((prefix1 != 0) + (prefix2 != 0) + zerofill + digits.length);
     if (spacesToPrint > 0) // need to do some padding
     {
-        if (leftPad == '0')
-        {
-            // pad with zeros
+        if (padChar == '0')
+            zerofill += spacesToPrint;
+        else if (padChar)
+            leftpad = spacesToPrint;
+        else
+            rightpad = spacesToPrint;
+    }
 
-            fs.precision =
-                cast(typeof(fs.precision)) (spacesToPrint + digits.length);
-                //to!(typeof(fs.precision))(spacesToPrint + digits.length);
-        }
-        else if (leftPad) foreach (i ; 0 .. spacesToPrint) put(w, ' ');
-    }
-    // write sign
-    if (forcedPrefix) put(w, forcedPrefix);
-    // write 0x or 0X
-    if (base == 16 && fs.flHash && arg) {
-        // @@@ overcome bug in dmd;
-        //w.write(fs.spec == 'x' ? "0x" : "0X"); //crashes the compiler
+    /**** Print ****/
+
+    foreach (i ; 0 .. leftpad)
+        put(w, ' ');
+
+    if (prefix1) put(w, prefix1);
+    if (prefix2) put(w, prefix2);
+
+    foreach (i ; 0 .. zerofill)
         put(w, '0');
-        put(w, fs.spec == 'x' ? 'x' : 'X'); // x or X
-    }
-    // write the digits
-    if (arg || fs.precision)
-    {
-        ptrdiff_t zerosToPrint = fs.precision - digits.length;
-        foreach (i ; 0 .. zerosToPrint) put(w, '0');
-        put(w, digits);
-    }
-    // write the spaces to the right if left-align
-    if (!leftPad) foreach (i ; 0 .. spacesToPrint) put(w, ' ');
+
+    put(w, digits);
+
+    foreach (i ; 0 .. rightpad)
+        put(w, ' ');
 }
 
 @safe pure unittest