fop/src/org/apache/fop/fo/expr/Numeric.java

/*-- $Id$ -- 

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package org.apache.fop.fo.expr;


import org.apache.fop.fo.Property;
import org.apache.fop.datatypes.Length;
import org.apache.fop.datatypes.PercentLength;
import org.apache.fop.datatypes.LinearCombinationLength;
import org.apache.fop.datatypes.MixedLength;
import org.apache.fop.datatypes.TableColLength;
import org.apache.fop.datatypes.PercentBase;

/**
 * Represents a "numeric" value as defined by the XSL FO Specification.
 * This consists of one or more kinds of value specifications, from
 * absolute numbers (units power of 0) to lengths (unit power of 1),
 * relative lengths (ems), percentage lengths.
 * A Numeric can be constructed from other Property types representing
 * Numbers or Length-type values.
 * Numeric provides methods to return Number and Length values based on
 * its current value.
 * It supports basic arithmetic operations involving Numerics.
 */
public class Numeric {
  // Bit fields
  public static final int ABS_LENGTH = 1;  // abs units (or number)
  public static final int PC_LENGTH=2;    // Percentage
  public static final int TCOL_LENGTH=4;  // Table units

  private int valType ;
  private double absValue ;
  private double pcValue ;
  private PercentBase pcBase=null; // base value for PC_LENGTH component
  private double tcolValue;
  private int    dim;


  /**
   * Construct a Numeric object by specifying one or more components,
   * including absolute length, percent length, table units.
   * @param valType A combination of bits representing the value types.
   * @param absValue The value of a Number or resolved Length value if
   * the ABS_LENGTH flag is set.
   * @param pcValue The decimal percent value if the PC_LENGTH flag is set
   * @param tcolValue The decimal table unit value if the TCOL_LENGTH flag
   * is set.
   * @param dim The dimension of the value. 0 for a Number, 1 for a Length
   * (any type), >1, <0 if Lengths have been multiplied or divided.
   * @pcBase The PercentBase object used to calculate an actual value for
   * a PC_LENGTH.
   */
  protected Numeric(int valType, double absValue, 
		 double pcValue, double tcolValue, int dim,
		    PercentBase pcBase) {
    this.valType = valType;
    this.absValue = absValue;
    this.pcValue = pcValue;
    this.tcolValue = tcolValue;
    this.dim = dim;
    this.pcBase = pcBase;
  }

  /**
   * Construct a Numeric object of dimension 0 from a double.
   * @param valType A combination of bits representing the value types.
   * @param absValue The value of a Number or resolved Length value.
   */
  /***
  protected Numeric(int valType, double absValue) {
    this.valType = valType;
    this.absValue = absValue;
  }
  ***/

  /**
   * Construct a Numeric object from a Number.
   * @param num The number.
   */
  public Numeric(Number num) {
    this(ABS_LENGTH, num.doubleValue(), 0.0, 0.0, 0, null);
  }

  /**
   * Construct a Numeric object from a Length.
   * @param l The Length.
   */
  public Numeric(Length l) {
    this(ABS_LENGTH, (double)l.mvalue(), 0.0, 0.0, 1, null);
  }

  /**
   * Construct a Numeric object from a PercentLength.
   * @param pclen The PercentLength.
   */
  public Numeric(PercentLength pclen) {
    this(PC_LENGTH,  0.0, pclen.value(), 0.0, 1, pclen.getBaseLength());
  }

  /**
   * Construct a Numeric object from a TableColLength.
   * @param tclen The TableColLength.
   */
  public Numeric(TableColLength tclen) {
    this(TCOL_LENGTH,  0.0, 0.0, tclen.getTableUnits(), 1, null);
  }


  /**
   * Return the current value as a Length if possible. This constructs
   * a new Length or Length subclass based on the current value type
   * of the Numeric.
   * If the stored value has a unit dimension other than 1, null
   * is returned.
   */
  public Length asLength() {
    if (dim == 1) {
      if (valType == ABS_LENGTH) {
	return new Length((int)absValue);
      }
      PercentLength pclen = null;
      if ((valType & PC_LENGTH)!=0)  {
	pclen = new PercentLength(pcValue, pcBase);
        if (valType == PC_LENGTH)
	  return pclen;
      }
      if ((valType & TCOL_LENGTH) != 0) {
	return new TableColLength((int)absValue, pclen, tcolValue);
      }
      return new MixedLength((int)absValue, pclen);
    }
    else {
      // or throw exception???
      // can't make Length if dimension != 1
      return null;
    }
  }
  /**
   * Return the current value as a Number if possible. 
   * Calls asDouble().
   */
  public Number asNumber() {
    return asDouble();
  }

  public Double asDouble() {
    if (dim == 0 && valType==ABS_LENGTH) {
      return new Double(absValue);
    }
    else {
      // or throw exception???
      // can't make Number if dimension != 0
      return null;
    }
  }

  /**
   * Return the current value as a Integer if possible.
   * If the unit dimension is 0 and the value type is ABSOLUTE, an Integer
   * is returned. Otherwise null is returned. Note: the current value is
   * truncated if necessary to make an integer value.
   */
  /**
  public Integer asInteger() {
    if (dim == 0 && valType==ABS_LENGTH) {
      return new Integer((int)absValue);
    }
    else {
      // or throw exception???
      // can't make Number if dimension != 0
      return null;
    }
  }
  **/

  /**
   * Return a boolean value indiciating whether the currently stored
   * value consists of different "types" of values (absolute, percent,
   * and/or table-unit.)
   */
  private boolean isMixedType() {
    int ntype = 0;
    for (int t = valType; t!=0; t=t>>1) {
      if ((t & 1) != 0) ++ntype;
    }
    return ntype>1;
  }

  /**
   * Subtract the operand from the current value and return a new Numeric
   * representing the result.
   * @param op The value to subtract.
   * @return A Numeric representing the result.
   * @throws PropertyException If the dimension of the operand is different
   * from the dimension of this Numeric.
   */
  public Numeric subtract(Numeric op) throws PropertyException {
    // Check of same dimension
    // Add together absolute and table units
    // What about percentages??? Treat as colUnits if they can't be
    // in same property!
    if (dim == op.dim) {
      PercentBase npcBase = ((valType & PC_LENGTH)!=0)? pcBase : op.pcBase;
      // Subtract each type of value
      return new Numeric(valType|op.valType, absValue-op.absValue,
			 pcValue-op.pcValue,
			 tcolValue-op.tcolValue,dim, npcBase);
    }
    else {
      throw new PropertyException("Can't add Numerics of different dimensions");
    }
  }
  /**
   * Add the operand from the current value and return a new Numeric
   * representing the result.
   * @param op The value to add.
   * @return A Numeric representing the result.
   * @throws PropertyException If the dimension of the operand is different
   * from the dimension of this Numeric.
   */
  public Numeric add(Numeric op) throws PropertyException {
    // Check of same dimension
    // Add together absolute and table units
    // What about percentages??? Treat as colUnits if they can't be
    // in same property!
    if (dim == op.dim) {
      PercentBase npcBase = ((valType & PC_LENGTH)!=0)? pcBase : op.pcBase;
      // Add each type of value
      return new Numeric(valType | op.valType, absValue+op.absValue,
			 pcValue+op.pcValue,
			 tcolValue+op.tcolValue, dim, npcBase);
    }
    else {
      throw new PropertyException("Can't add Numerics of different dimensions");
    }
  }

  /**
   * Multiply the the current value by the operand and return a new Numeric
   * representing the result.
   * @param op The multiplier.
   * @return A Numeric representing the result.
   * @throws PropertyException If both Numerics have "mixed" type.
   */
  public Numeric multiply(Numeric op) throws PropertyException {
    // Multiply together absolute units and add dimensions (exponents)
    // What about percentages??? Treat as colUnits if they can't be
    // in same property!
    if (dim == 0) {
      // This is a dimensionless quantity, ie. a "Number"
      return new Numeric(op.valType, absValue*op.absValue,
			 absValue*op.pcValue,
			 absValue*op.tcolValue, op.dim,
			 op.pcBase);
    }
    else if (op.dim == 0) {
      double opval = op.absValue;
      return new Numeric(valType, opval*absValue,
			 opval*pcValue, opval*tcolValue, dim, pcBase);
    }
    else if (valType == op.valType && !isMixedType()) {
      // Check same relbase and pcbase ???
      PercentBase npcBase = ((valType & PC_LENGTH)!=0)? pcBase : op.pcBase;
      return new Numeric(valType, absValue * op.absValue,
			 pcValue*op.pcValue,
			 tcolValue*op.tcolValue,dim+op.dim,
			 npcBase);
    }
    else {
      throw new PropertyException("Can't multiply mixed Numerics");
    }
  }

  /**
   * Divide the the current value by the operand and return a new Numeric
   * representing the result.
   * @param op The divisor.
   * @return A Numeric representing the result.
   * @throws PropertyException If both Numerics have "mixed" type.
   */
  public Numeric divide(Numeric op) throws PropertyException {
    // Multiply together absolute units and add dimensions (exponents)
    // What about percentages??? Treat as colUnits if they can't be
    // in same property!
    if (dim == 0) {
      // This is a dimensionless quantity, ie. a "Number"
      return new Numeric(op.valType, absValue/op.absValue,
			 absValue/op.pcValue,
			 absValue/op.tcolValue, -op.dim, op.pcBase);
    }
    else if (op.dim == 0) {
      double opval = op.absValue;
      return new Numeric(valType, absValue/opval,
			 pcValue/opval, tcolValue/opval, dim, pcBase);
    }
    else if (valType == op.valType && !isMixedType()) {
      PercentBase npcBase = ((valType & PC_LENGTH)!=0)? pcBase : op.pcBase;
      return new Numeric(valType,
			 (valType==ABS_LENGTH? absValue/op.absValue:0.0),
			 (valType==PC_LENGTH? pcValue/op.pcValue:0.0),
			 (valType==TCOL_LENGTH? tcolValue/op.tcolValue:0.0),
			 dim-op.dim, npcBase);
    }
    else {
      throw new PropertyException("Can't divide mixed Numerics.");
    }
  }

  /**
   * Return the absolute value of this Numeric.
   * @return A new Numeric object representing the absolute value.
   */
  public Numeric abs() {
    return new Numeric(valType, Math.abs(absValue),
		       Math.abs(pcValue), Math.abs(tcolValue), dim, pcBase);
  }

  /**
   * Return a Numeric which is the maximum of the current value and the
   * operand.
   * @throws PropertyException If the dimensions or value types of the
   * object and the operand are different.
   */
  public Numeric max(Numeric op) throws PropertyException {
    double rslt = 0.0;
    // Only compare if have same dimension and value type!
    if (dim == op.dim && valType == op.valType && !isMixedType()) {
      if (valType==ABS_LENGTH) rslt = absValue - op.absValue;
      else if (valType==PC_LENGTH) rslt = pcValue - op.pcValue;
      else if (valType==TCOL_LENGTH) rslt = tcolValue - op.tcolValue;
      if (rslt > 0.0)
	return this;
      else return op;
    }
    throw new PropertyException("Arguments to max() must have same dimension and value type.");
  }

   /**
   * Return a Numeric which is the minimum of the current value and the
   * operand.
   * @throws PropertyException If the dimensions or value types of the
   * object and the operand are different.
   */
  public Numeric min(Numeric op) throws PropertyException {
    double rslt = 0.0;
    // Only compare if have same dimension and value type!
    if (dim == op.dim && valType == op.valType && !isMixedType()) {
      if (valType==ABS_LENGTH) rslt = absValue - op.absValue;
      else if (valType==PC_LENGTH) rslt = pcValue - op.pcValue;
      else if (valType==TCOL_LENGTH) rslt = tcolValue - op.tcolValue;
      if (rslt > 0.0)
	return op;
      else return this;
    }
    throw new PropertyException("Arguments to min() must have same dimension and value type.");
  }

}