Merge pull request #82 from dscho/dates

Implement date parsing / formatting

classpath/java/text/ParseException.java

@@ -0,0 +1,24 @@
+/* Copyright (c) 2008-2013, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package java.text;
+
+public class ParseException extends Exception {
+  private int errorOffset;
+
+  public ParseException(String message, int errorOffset) {
+    super(message);
+    this.errorOffset = errorOffset;
+  }
+
+  public int getErrorOffset() {
+    return errorOffset;
+  }
+}

classpath/java/text/ParsePosition.java

@@ -0,0 +1,39 @@
+/* Copyright (c) 2008-2013, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package java.text;
+
+public class ParsePosition {
+  private int index, errorIndex = -1;
+
+  public ParsePosition(int index) {
+    this.index = index;
+  }
+
+  public int getErrorIndex() {
+    return errorIndex;
+  }
+
+  public int getIndex() {
+    return index;
+  }
+
+  public void setErrorIndex(int i) {
+    errorIndex = i;
+  }
+
+  public void setIndex(int i) {
+    index = i;
+  }
+
+  public String toString() {
+    return "index: " + index + "(error index: " + errorIndex + ")";
+  }
+}

classpath/java/text/SimpleDateFormat.java

@@ -0,0 +1,98 @@
+/* Copyright (c) 2008-2013, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package java.text;
+
+import java.util.Calendar;
+import java.util.Date;
+
+public class SimpleDateFormat {
+  private String pattern;
+
+  public SimpleDateFormat(String pattern) {
+    this.pattern = pattern;
+    if (! "yyyy-MM-dd'T'HH:mm:ss".equals(pattern)) {
+      throw new UnsupportedOperationException("Unsupported pattern: " + pattern);
+    }
+  }
+
+  public StringBuffer format(Date date, StringBuffer buffer, FieldPosition position) {
+    Calendar calendar = Calendar.getInstance();
+    calendar.setTime(date);
+    pad(buffer, calendar.get(Calendar.YEAR), 4);
+    buffer.append('-');
+    pad(buffer, calendar.get(Calendar.MONTH) + 1, 2);
+    buffer.append('-');
+    pad(buffer, calendar.get(Calendar.DAY_OF_MONTH), 2);
+    buffer.append("T");
+    pad(buffer, calendar.get(Calendar.HOUR_OF_DAY), 2);
+    buffer.append(':');
+    pad(buffer, calendar.get(Calendar.MINUTE), 2);
+    buffer.append(':');
+    pad(buffer, calendar.get(Calendar.SECOND), 2);
+    return buffer;
+  }
+
+  public Date parse(String text) {
+    return parse(text, new ParsePosition(0));
+  }
+
+  public Date parse(String text, ParsePosition position) {
+    int index = position.getIndex();
+    try {
+      Calendar calendar = Calendar.getInstance();
+      index = parseField(text, index, 4, calendar, Calendar.YEAR, 0);
+      index = expectPrefix(text, index, "-");
+      index = parseField(text, index, 2, calendar, Calendar.MONTH, -1);
+      index = expectPrefix(text, index, "-");
+      index = parseField(text, index, 2, calendar, Calendar.DAY_OF_MONTH, 0);
+      index = expectPrefix(text, index, "T");
+      index = parseField(text, index, 2, calendar, Calendar.HOUR_OF_DAY, 0);
+      index = expectPrefix(text, index, ":");
+      index = parseField(text, index, 2, calendar, Calendar.MINUTE, 0);
+      index = expectPrefix(text, index, ":");
+      index = parseField(text, index, 2, calendar, Calendar.SECOND, 0);
+      position.setIndex(index);
+      return calendar.getTime();
+    } catch (ParseException e) {
+      position.setErrorIndex(index);
+      return null;
+    }
+  }
+
+  private static void pad(StringBuffer buffer, int value, int digits) {
+    int i = value == 0 ? 1 : value;
+    while (i > 0) {
+      i /= 10;
+      --digits;
+    }
+    while (digits-- > 0) {
+      buffer.append('0');
+    }
+    buffer.append(value);
+  }
+
+  private static int parseField(String text, int offset, int length, Calendar calendar, int field, int adjustment) throws ParseException {
+    if (text.length() < offset + length) throw new ParseException("Short date: " + text, offset);
+    try {
+      int value = Integer.parseInt(text.substring(offset, offset + length), 10);
+      calendar.set(field, value + adjustment);
+    } catch (NumberFormatException e) {
+      throw new ParseException("Not a number: " + text, offset);
+    }
+    return offset + length;
+  }
+
+  private static int expectPrefix(String text, int offset, String prefix) throws ParseException {
+    if (text.length() <= offset) throw new ParseException("Short date: " + text, offset);
+    if (! text.substring(offset).startsWith(prefix)) throw new ParseException("Parse error: " + text, offset);
+    return offset + prefix.length();
+  }
+}

classpath/java/util/Calendar.java

@@ -55,6 +55,10 @@ public abstract class Calendar {
     time = date.getTime();
   }
 
+  public Date getTime() {
+    return new Date(time);
+  }
+
   public abstract void roll(int field, boolean up);
   public abstract void add(int field, int amount);
 
@@ -102,6 +106,23 @@ public abstract class Calendar {
       parseIntoFields(this.time);
     }
 
+    public Date getTime() {
+      long days = fields[DAY_OF_MONTH] - 1;
+      long years = fields[YEAR] - EPOCH_LEAP_YEAR;
+      days += years * 365 + years / 4 + 1 - DAYS_TO_EPOCH;
+      for (int month = 0; month < fields[MONTH]; month++) {
+        days += DAYS_IN_MONTH[0][month];
+      }
+      if (fields[MONTH] < 2 && isLeapYear(fields[YEAR])) {
+        days--;
+      }
+      long time = MILLIS_PER_DAY * days
+        + MILLIS_PER_HOUR * fields[HOUR_OF_DAY]
+        + MILLIS_PER_MINUTE * fields[MINUTE]
+        + MILLIS_PER_SECOND * fields[SECOND];
+      return new Date(time);
+    }
+
     private static boolean isLeapYear(int year) {
       return (year%4 == 0) && (year%100 != 0) || (year%400 == 0);
     }

test/Dates.java

@@ -0,0 +1,25 @@
+import java.text.FieldPosition;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+
+public class Dates {
+  private final static long EPOCH = 1234567890;
+  private final static String TEXT = "2009-02-13T23:31:30";
+
+  private static void expect(boolean v) {
+    if (! v) throw new RuntimeException();
+  }
+
+  public static void main(String[] args) throws Exception {
+    SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
+    Date date = format.parse("1970-01-01T00:00:00");
+    expect(0 == date.getTime());
+
+    date = new Date(EPOCH * 1000l);
+    String actual = format.format(date, new StringBuffer(), new FieldPosition(0)).toString();
+    expect(TEXT.equals(actual));
+
+    date = format.parse(TEXT);
+    expect(EPOCH == date.getTime() / 1000l);
+  }
+}