001: /*
002: * Copyright 1999-2004 The Apache Software Foundation.
003: *
004: * Licensed under the Apache License, Version 2.0 (the "License");
005: * you may not use this file except in compliance with the License.
006: * You may obtain a copy of the License at
007: *
008: * http://www.apache.org/licenses/LICENSE-2.0
009: *
010: * Unless required by applicable law or agreed to in writing, software
011: * distributed under the License is distributed on an "AS IS" BASIS,
012: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013: * See the License for the specific language governing permissions and
014: * limitations under the License.
015: */
016: /*
017: * $Id: XNumber.java,v 1.21 2005/01/23 01:08:21 mcnamara Exp $
018: */
019: package org.apache.xpath.objects;
020:
021: import org.apache.xpath.ExpressionOwner;
022: import org.apache.xpath.XPathContext;
023: import org.apache.xpath.XPathVisitor;
024:
025: /**
026: * This class represents an XPath number, and is capable of
027: * converting the number to other types, such as a string.
028: * @xsl.usage general
029: */
030: public class XNumber extends XObject {
031: static final long serialVersionUID = -2720400709619020193L;
032:
033: /** Value of the XNumber object.
034: * @serial */
035: double m_val;
036:
037: /**
038: * Construct a XNodeSet object.
039: *
040: * @param d Value of the object
041: */
042: public XNumber(double d) {
043: super ();
044:
045: m_val = d;
046: }
047:
048: /**
049: * Construct a XNodeSet object.
050: *
051: * @param num Value of the object
052: */
053: public XNumber(Number num) {
054:
055: super ();
056:
057: m_val = num.doubleValue();
058: m_obj = num;
059: }
060:
061: /**
062: * Tell that this is a CLASS_NUMBER.
063: *
064: * @return node type CLASS_NUMBER
065: */
066: public int getType() {
067: return CLASS_NUMBER;
068: }
069:
070: /**
071: * Given a request type, return the equivalent string.
072: * For diagnostic purposes.
073: *
074: * @return type string "#NUMBER"
075: */
076: public String getTypeString() {
077: return "#NUMBER";
078: }
079:
080: /**
081: * Cast result object to a number.
082: *
083: * @return the value of the XNumber object
084: */
085: public double num() {
086: return m_val;
087: }
088:
089: /**
090: * Evaluate expression to a number.
091: *
092: * @return 0.0
093: *
094: * @throws javax.xml.transform.TransformerException
095: */
096: public double num(XPathContext xctxt)
097: throws javax.xml.transform.TransformerException {
098:
099: return m_val;
100: }
101:
102: /**
103: * Cast result object to a boolean.
104: *
105: * @return false if the value is NaN or equal to 0.0
106: */
107: public boolean bool() {
108: return (Double.isNaN(m_val) || (m_val == 0.0)) ? false : true;
109: }
110:
111: // /**
112: // * Cast result object to a string.
113: // *
114: // * @return "NaN" if the number is NaN, Infinity or -Infinity if
115: // * the number is infinite or the string value of the number.
116: // */
117: // private static final int PRECISION = 16;
118: // public String str()
119: // {
120: //
121: // if (Double.isNaN(m_val))
122: // {
123: // return "NaN";
124: // }
125: // else if (Double.isInfinite(m_val))
126: // {
127: // if (m_val > 0)
128: // return "Infinity";
129: // else
130: // return "-Infinity";
131: // }
132: //
133: // long longVal = (long)m_val;
134: // if ((double)longVal == m_val)
135: // return Long.toString(longVal);
136: //
137: //
138: // String s = Double.toString(m_val);
139: // int len = s.length();
140: //
141: // if (s.charAt(len - 2) == '.' && s.charAt(len - 1) == '0')
142: // {
143: // return s.substring(0, len - 2);
144: // }
145: //
146: // int exp = 0;
147: // int e = s.indexOf('E');
148: // if (e != -1)
149: // {
150: // exp = Integer.parseInt(s.substring(e + 1));
151: // s = s.substring(0,e);
152: // len = e;
153: // }
154: //
155: // // Calculate Significant Digits:
156: // // look from start of string for first digit
157: // // look from end for last digit
158: // // significant digits = end - start + (0 or 1 depending on decimal location)
159: //
160: // int decimalPos = -1;
161: // int start = (s.charAt(0) == '-') ? 1 : 0;
162: // findStart: for( ; start < len; start++ )
163: // {
164: // switch (s.charAt(start))
165: // {
166: // case '0':
167: // break;
168: // case '.':
169: // decimalPos = start;
170: // break;
171: // default:
172: // break findStart;
173: // }
174: // }
175: // int end = s.length() - 1;
176: // findEnd: for( ; end > start; end-- )
177: // {
178: // switch (s.charAt(end))
179: // {
180: // case '0':
181: // break;
182: // case '.':
183: // decimalPos = end;
184: // break;
185: // default:
186: // break findEnd;
187: // }
188: // }
189: //
190: // int sigDig = end - start;
191: //
192: // // clarify decimal location if it has not yet been found
193: // if (decimalPos == -1)
194: // decimalPos = s.indexOf('.');
195: //
196: // // if decimal is not between start and end, add one to sigDig
197: // if (decimalPos < start || decimalPos > end)
198: // ++sigDig;
199: //
200: // // reduce significant digits to PRECISION if necessary
201: // if (sigDig > PRECISION)
202: // {
203: // // re-scale BigDecimal in order to get significant digits = PRECISION
204: // BigDecimal num = new BigDecimal(s);
205: // int newScale = num.scale() - (sigDig - PRECISION);
206: // if (newScale < 0)
207: // newScale = 0;
208: // s = num.setScale(newScale, BigDecimal.ROUND_HALF_UP).toString();
209: //
210: // // remove trailing '0's; keep track of decimalPos
211: // int truncatePoint = s.length();
212: // while (s.charAt(--truncatePoint) == '0')
213: // ;
214: //
215: // if (s.charAt(truncatePoint) == '.')
216: // {
217: // decimalPos = truncatePoint;
218: // }
219: // else
220: // {
221: // decimalPos = s.indexOf('.');
222: // truncatePoint += 1;
223: // }
224: //
225: // s = s.substring(0, truncatePoint);
226: // len = s.length();
227: // }
228: //
229: // // Account for exponent by adding zeros as needed
230: // // and moving the decimal place
231: //
232: // if (exp == 0)
233: // return s;
234: //
235: // start = 0;
236: // String sign;
237: // if (s.charAt(0) == '-')
238: // {
239: // sign = "-";
240: // start++;
241: // }
242: // else
243: // sign = "";
244: //
245: // String wholePart = s.substring(start, decimalPos);
246: // String decimalPart = s.substring(decimalPos + 1);
247: //
248: // // get the number of digits right of the decimal
249: // int decimalLen = decimalPart.length();
250: //
251: // if (exp >= decimalLen)
252: // return sign + wholePart + decimalPart + zeros(exp - decimalLen);
253: //
254: // if (exp > 0)
255: // return sign + wholePart + decimalPart.substring(0, exp) + "."
256: // + decimalPart.substring(exp);
257: //
258: // return sign + "0." + zeros(-1 - exp) + wholePart + decimalPart;
259: // }
260:
261: /**
262: * Cast result object to a string.
263: *
264: * @return "NaN" if the number is NaN, Infinity or -Infinity if
265: * the number is infinite or the string value of the number.
266: */
267: public String str() {
268:
269: if (Double.isNaN(m_val)) {
270: return "NaN";
271: } else if (Double.isInfinite(m_val)) {
272: if (m_val > 0)
273: return "Infinity";
274: else
275: return "-Infinity";
276: }
277:
278: double num = m_val;
279: String s = Double.toString(num);
280: int len = s.length();
281:
282: if (s.charAt(len - 2) == '.' && s.charAt(len - 1) == '0') {
283: s = s.substring(0, len - 2);
284:
285: if (s.equals("-0"))
286: return "0";
287:
288: return s;
289: }
290:
291: int e = s.indexOf('E');
292:
293: if (e < 0) {
294: if (s.charAt(len - 1) == '0')
295: return s.substring(0, len - 1);
296: else
297: return s;
298: }
299:
300: int exp = Integer.parseInt(s.substring(e + 1));
301: String sign;
302:
303: if (s.charAt(0) == '-') {
304: sign = "-";
305: s = s.substring(1);
306:
307: --e;
308: } else
309: sign = "";
310:
311: int nDigits = e - 2;
312:
313: if (exp >= nDigits)
314: return sign + s.substring(0, 1) + s.substring(2, e)
315: + zeros(exp - nDigits);
316:
317: // Eliminate trailing 0's - bugzilla 14241
318: while (s.charAt(e - 1) == '0')
319: e--;
320:
321: if (exp > 0)
322: return sign + s.substring(0, 1) + s.substring(2, 2 + exp)
323: + "." + s.substring(2 + exp, e);
324:
325: return sign + "0." + zeros(-1 - exp) + s.substring(0, 1)
326: + s.substring(2, e);
327: }
328:
329: /**
330: * Return a string of '0' of the given length
331: *
332: *
333: * @param n Length of the string to be returned
334: *
335: * @return a string of '0' with the given length
336: */
337: static private String zeros(int n) {
338: if (n < 1)
339: return "";
340:
341: char[] buf = new char[n];
342:
343: for (int i = 0; i < n; i++) {
344: buf[i] = '0';
345: }
346:
347: return new String(buf);
348: }
349:
350: /**
351: * Return a java object that's closest to the representation
352: * that should be handed to an extension.
353: *
354: * @return The value of this XNumber as a Double object
355: */
356: public Object object() {
357: if (null == m_obj)
358: m_obj = new Double(m_val);
359: return m_obj;
360: }
361:
362: /**
363: * Tell if two objects are functionally equal.
364: *
365: * @param obj2 Object to compare this to
366: *
367: * @return true if the two objects are equal
368: *
369: * @throws javax.xml.transform.TransformerException
370: */
371: public boolean equals(XObject obj2) {
372:
373: // In order to handle the 'all' semantics of
374: // nodeset comparisons, we always call the
375: // nodeset function.
376: int t = obj2.getType();
377: try {
378: if (t == XObject.CLASS_NODESET)
379: return obj2.equals(this );
380: else if (t == XObject.CLASS_BOOLEAN)
381: return obj2.bool() == bool();
382: else
383: return m_val == obj2.num();
384: } catch (javax.xml.transform.TransformerException te) {
385: throw new org.apache.xml.utils.WrappedRuntimeException(te);
386: }
387: }
388:
389: /**
390: * Tell if this expression returns a stable number that will not change during
391: * iterations within the expression. This is used to determine if a proximity
392: * position predicate can indicate that no more searching has to occur.
393: *
394: *
395: * @return true if the expression represents a stable number.
396: */
397: public boolean isStableNumber() {
398: return true;
399: }
400:
401: /**
402: * @see org.apache.xpath.XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor)
403: */
404: public void callVisitors(ExpressionOwner owner, XPathVisitor visitor) {
405: visitor.visitNumberLiteral(owner, this);
406: }
407:
408: }
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