classlib: implement float support for String.format (#873)

classlib/src/main/java/org/teavm/classlib/java/text/TDecimalFormat.java

@@ -245,7 +245,7 @@ public class TDecimalFormat extends TNumberFormat {
             if (digit >= 0 && digit <= 9) {
                 if (!fractionalPart) {
                     ++intSize;
-                    allowGroupSeparator = groupingSize > 1;
+                    allowGroupSeparator = isGroupingUsed() && groupingSize > 1;
                 } else {
                     ++fracSize;
                 }
@@ -383,7 +383,7 @@ public class TDecimalFormat extends TNumberFormat {
             if (digit >= 0 && digit <= 9) {
                 if (!fractionalPart) {
                     ++intSize;
-                    allowGroupSeparator = groupingSize > 1;
+                    allowGroupSeparator = isGroupingUsed() && groupingSize > 1;
                 } else {
                     ++fracSize;
                 }
@@ -710,7 +710,7 @@ public class TDecimalFormat extends TNumberFormat {
         int digitPos = Math.max(intLength, getMinimumIntegerDigits()) - 1;
         for (int i = getMinimumIntegerDigits() - 1; i >= intLength; --i) {
             buffer.append('0');
-            if (groupingSize > 0 && digitPos % groupingSize == 0 && digitPos > 0) {
+            if (isGroupingUsed() && groupingSize > 0 && digitPos % groupingSize == 0 && digitPos > 0) {
                 buffer.append(symbols.getGroupingSeparator());
             }
             --digitPos;
@@ -723,7 +723,7 @@ public class TDecimalFormat extends TNumberFormat {
             long mantissaDigitMask = POW10_ARRAY[mantissaDigit--];
             buffer.append(forDigit(Math.abs((int) (mantissa / mantissaDigitMask))));
             mantissa %= mantissaDigitMask;
-            if (groupingSize > 0 && digitPos % groupingSize == 0 && digitPos > 0) {
+            if (isGroupingUsed() && groupingSize > 0 && digitPos % groupingSize == 0 && digitPos > 0) {
                 buffer.append(symbols.getGroupingSeparator());
             }
             --digitPos;
@@ -733,7 +733,7 @@ public class TDecimalFormat extends TNumberFormat {
         intLength -= significantIntDigits;
         for (int i = 0; i < intLength; ++i) {
             buffer.append('0');
-            if (groupingSize > 0 && digitPos % groupingSize == 0 && digitPos > 0) {
+            if (isGroupingUsed() && groupingSize > 0 && digitPos % groupingSize == 0 && digitPos > 0) {
                 buffer.append(symbols.getGroupingSeparator());
             }
             --digitPos;
@@ -901,7 +901,7 @@ public class TDecimalFormat extends TNumberFormat {
         int digitPos = Math.max(intLength, getMinimumIntegerDigits()) - 1;
         for (int i = getMinimumIntegerDigits() - 1; i >= intLength; --i) {
             buffer.append('0');
-            if (groupingSize > 0 && digitPos % groupingSize == 0 && digitPos > 0) {
+            if (isGroupingUsed() && groupingSize > 0 && digitPos % groupingSize == 0 && digitPos > 0) {
                 buffer.append(symbols.getGroupingSeparator());
             }
             --digitPos;
@@ -914,7 +914,7 @@ public class TDecimalFormat extends TNumberFormat {
             BigInteger[] parts = mantissa.divideAndRemainder(mantissaDigitMask);
             buffer.append(forDigit(Math.abs(parts[0].intValue())));
             mantissa = parts[1];
-            if (groupingSize > 0 && digitPos % groupingSize == 0 && digitPos > 0) {
+            if (isGroupingUsed() && groupingSize > 0 && digitPos % groupingSize == 0 && digitPos > 0) {
                 buffer.append(symbols.getGroupingSeparator());
             }
             --digitPos;
@@ -926,7 +926,7 @@ public class TDecimalFormat extends TNumberFormat {
         intLength -= significantIntDigits;
         for (int i = 0; i < intLength; ++i) {
             buffer.append('0');
-            if (groupingSize > 0 && digitPos % groupingSize == 0 && digitPos > 0) {
+            if (isGroupingUsed() && groupingSize > 0 && digitPos % groupingSize == 0 && digitPos > 0) {
                 buffer.append(symbols.getGroupingSeparator());
             }
             --digitPos;

classlib/src/main/java/org/teavm/classlib/java/util/TFormatter.java

@@ -22,6 +22,7 @@ import java.io.OutputStream;
 import java.io.OutputStreamWriter;
 import java.io.PrintStream;
 import java.io.UnsupportedEncodingException;
+import java.math.BigDecimal;
 import java.text.DecimalFormat;
 import java.text.DecimalFormatSymbols;
 import java.text.NumberFormat;
@@ -31,6 +32,7 @@ import java.util.IllegalFormatConversionException;
 import java.util.Locale;
 import java.util.UnknownFormatConversionException;
 import org.teavm.classlib.impl.IntegerUtil;
+import org.teavm.classlib.java.text.TDecimalFormat;
 
 public final class TFormatter implements Closeable, Flushable {
     private Locale locale;
@@ -240,11 +242,98 @@ public final class TFormatter implements Closeable, Flushable {
                     formatRadixInt(specifier, 4, true);
                     break;
 
+                case 'f':
+                    formatFloat(specifier, false);
+                    break;
+
                 default:
                     throw new UnknownFormatConversionException(String.valueOf(specifier));
             }
         }
 
+        private void formatFloat(char specifier, boolean upperCase) throws IOException {
+            verifyFlags(specifier, MASK_FOR_INT_DECIMAL_FORMAT);
+            verifyFloatFlags();
+
+            if (precision == -1) {
+                precision = 6;
+            }
+
+            Object arg = args[argumentIndex];
+            boolean negative;
+            if (arg instanceof Double) {
+                negative = (Double) arg < 0;
+            } else if (arg instanceof Float) {
+                negative = (Float) arg < 0;
+            } else if (arg instanceof BigDecimal) {
+                negative = ((BigDecimal) arg).signum() < 0;
+            } else {
+                throw new IllegalFormatConversionException(specifier, arg == null ? null : arg.getClass());
+            }
+
+            TDecimalFormat format = new TDecimalFormat();
+            format.setDecimalFormatSymbols(new DecimalFormatSymbols(locale));
+            if (width != -1) {
+                int decimalSize = predictDecimalSize(negative, format);
+                format.setMaximumIntegerDigits(decimalSize);
+                if ((flags & TFormattableFlags.ZERO_PADDED) != 0) {
+                    format.setMinimumIntegerDigits(decimalSize);
+                }
+            }
+            format.setMaximumFractionDigits(precision);
+            format.setMinimumFractionDigits(precision);
+            format.setGroupingUsed((flags & TFormattableFlags.GROUPING_SEPARATOR) != 0);
+            if ((flags & TFormattableFlags.PARENTHESIZED_NEGATIVE) != 0) {
+                format.setNegativePrefix("(");
+                format.setNegativeSuffix(")");
+            }
+            if ((flags & TFormattableFlags.SIGNED) != 0) {
+                format.setPositivePrefix("+"); // DecimalFormatSymbols has no plus sign
+            } else if ((flags & TFormattableFlags.LEADING_SPACE) != 0) {
+                format.setPositivePrefix(" ");
+            }
+
+            String str = format.format(arg);
+
+            precision = -1; // prevent formatGivenString from trimming
+
+            formatGivenString(upperCase, str);
+        }
+
+        private int predictDecimalSize(boolean negative, TDecimalFormat format) {
+            int decimalSize = width;
+            if (precision > 0) {
+                decimalSize -= precision + 1; // width also includes decimal places. Subtract them!
+            }
+            // signs take up space as well. Also subtract them!
+            if (negative) {
+                if ((flags & TFormattableFlags.PARENTHESIZED_NEGATIVE) != 0) {
+                    decimalSize -= 2;
+                } else {
+                    decimalSize--;
+                }
+            } else if ((flags & (TFormattableFlags.SIGNED | TFormattableFlags.LEADING_SPACE)) != 0) {
+                decimalSize--;
+            }
+            // the grouping separator also takes up space. You know the drill.
+            if ((flags & TFormattableFlags.GROUPING_SEPARATOR) != 0) {
+                decimalSize -= decimalSize / (format.getGroupingSize() + 1);
+            }
+            return decimalSize;
+        }
+
+        private void verifyFloatFlags() {
+            if ((flags & TFormattableFlags.SIGNED) != 0 && (flags & TFormattableFlags.LEADING_SPACE) != 0) {
+                throw new TIllegalFormatFlagsException("+ ");
+            }
+            if ((flags & TFormattableFlags.ZERO_PADDED) != 0 && (flags & TFormattableFlags.LEFT_JUSTIFY) != 0) {
+                throw new TIllegalFormatFlagsException("0-");
+            }
+            if ((flags & TFormattableFlags.LEFT_JUSTIFY) != 0 && width < 0) {
+                throw new TMissingFormatWidthException(format.substring(formatSpecifierStart, index));
+            }
+        }
+
         private void formatBoolean(char specifier, boolean upperCase) throws IOException {
             verifyFlagsForGeneralFormat(specifier);
             Object arg = args[argumentIndex];

tests/src/test/java/org/teavm/classlib/java/text/DecimalFormatTest.java

@@ -479,6 +479,22 @@ public class DecimalFormatTest {
         assertEquals("23.00 RUB", format.format(23));
     }
 
+    @Test
+    public void formatsManual() {
+        DecimalFormat format = new DecimalFormat();
+        format.setDecimalFormatSymbols(new DecimalFormatSymbols(Locale.US));
+        format.setMaximumFractionDigits(6);
+        format.setMinimumFractionDigits(6);
+        format.setGroupingUsed(false);
+        assertEquals("1.200000", format.format((Object) 1.2));
+        assertEquals("12.200000", format.format((Object) 12.2));
+        format.setMaximumFractionDigits(0);
+        format.setMinimumFractionDigits(0);
+        format.setMaximumIntegerDigits(5);
+        format.setMinimumIntegerDigits(5);
+        assertEquals("00002", format.format((Object) 2.0));
+    }
+
     private DecimalFormat createFormat(String format) {
         return new DecimalFormat(format, symbols);
     }

tests/src/test/java/org/teavm/classlib/java/util/FormatterTest.java

@@ -253,4 +253,30 @@ public class FormatterTest {
             assertEquals(2, e.getPrecision());
         }
     }
+
+    @Test
+    public void formatsDouble() {
+        assertEquals("1.200000", new Formatter(Locale.US).format("%f", 1.2).toString());
+        assertEquals("12.200000", new Formatter(Locale.US).format("%f", 12.2).toString());
+
+        assertEquals("00002", new Formatter(Locale.US).format("%05.0f", 2.3).toString());
+        assertEquals("-0023", new Formatter(Locale.US).format("%05.0f", -23f).toString());
+        assertEquals("1,234.600000", new Formatter(Locale.US).format("%0,9f", 1234.6).toString());
+        assertEquals("(1,234.6)", new Formatter(Locale.US).format("%0,(9.1f", -1234.6).toString());
+
+        assertEquals("1 12 123 1,234 12,345 123,456 1,234,567", new Formatter(Locale.US)
+                .format("%,.0f %,.0f %,.0f %,.0f %,.0f %,.0f %,.0f", 1f, 12f, 123f, 1234f, 12345f, 123456f, 1234567f)
+                .toString());
+
+        assertEquals(" -123.1:-234.2 ", new Formatter(Locale.US)
+                .format("%7.1f:%-7.1f", -123.1, -234.2).toString());
+
+        assertEquals("+123.1 +123.2 +0.3", new Formatter(Locale.US)
+                .format("%+.1f %+05.1f %+.1f", 123.1, 123.2, 0.3).toString());
+
+        assertEquals(": 123.0:-123.0:", new Formatter(Locale.US)
+                .format(":% .1f:% .1f:", 123f, -123d).toString());
+
+        assertEquals("12.050", new Formatter(Locale.US).format("%4.3f", 12.05).toString());
+    }
 }