Package com.singularsys.jep

Class PrintVisitor

java.lang.Object
com.singularsys.jep.PrintVisitor
All Implemented Interfaces:
JepComponent, ParserVisitor, Serializable
Direct Known Subclasses:
PrintVisitor.NullPrintVisitor
public class PrintVisitor extends Object implements ParserVisitor, JepComponent
Prints an expression with configuration options.

By default, expressions are printed with only necessary bracketing. For example, if an expression "a+(b+c)" is parsed and printed, it will be printed as a+b+c since the bracketing does not affect the evaluation.

Enabling the FULL_BRACKET mode prints the expression with many brackets as ((-1.0)/sqrt((1.0-(x^2.0)))).

To use the PrintVisitor, you can invoke it through the Jep class as follows: 

 Jep j = ...; Node in = ...;
 j.print(in, "x");

You can also print expressions independently from the Jep class by using this class and calling the various print methods.

Since:
Dec 04 and NumberFormat object can be supplied to modify printing of numbers., Dec 04 PrintVisitor can now cope with 3 or more arguments to + and *., 3.3 greater customisation now possible, 4.0 Operators can implement PrintRulesI
Author:
Rich Morris Created on 20-Jun-2003
See Also:

  • Field Details

    • LBracket

      protected String LBracket

    • RBracket

      protected String RBracket

    • FunLBracket

      protected String FunLBracket

    • FunRBracket

      protected String FunRBracket

    • FunctionArgSep

      protected String FunctionArgSep

    • FULL_BRACKET

      public static final int FULL_BRACKET
      Enable this mode to print all brackets. Removes all ambiguity.
      See Also:

    • COMPLEX_I

      public static final int COMPLEX_I
      Enable this mode to print complex numbers as 3+2 i
      See Also:

    • sb

      protected transient StringBuffer sb

    • mode

      protected int mode
      The current mode for printing. Stores multiple flags as a bit field.

    • specialRules

      protected HashMap<Operator,PrintVisitor.PrintRulesI> specialRules

    • specialFunRules

      protected HashMap<String,PrintVisitor.PrintRulesI> specialFunRules

    • specialVarName

      protected HashMap<String,String> specialVarName

    • format

      protected NumberFormat format
      The NumberFormat object used to print numbers.

    • fp

      protected transient FieldPosition fp

    • ot

      protected OperatorTableI ot

    • NULL_PRINT_VISITOR

      public static final PrintVisitor.NullPrintVisitor NULL_PRINT_VISITOR
      A do-nothing PrintVisitor, useful for reducing memory usage when printing not required. This is static Singleton instance which can be safely be reused.
      Since:
      3.5

  • Constructor Details

    • PrintVisitor

      public PrintVisitor()
      Creates a visitor to create and print string representations of an expression tree.

  • Method Details

    • init

      public void init(Jep jep)
      Description copied from interface: JepComponent
      Initialize the component. This method is called whenever a component is added to Jep. Hence, it allows components to keep track of the other components they may rely on.
      Specified by:
      init in interface JepComponent
      Parameters:
      jep - the current Jep instance

    • print

      public void print(Node node, PrintStream out)
      Prints the tree descending from node with lots of brackets or specified stream.
      See Also:

    • printWrap

      public void printWrap(StringBuffer sb1, PrintStream out)
      Utility method to print a wrapped version of the output. Each line will be a maximum of maxLen characters wide with lines broken on
      Parameters:
      sb1 - the StringBuffer to print
      out - the output stream

    • print

      public void print(Node node)
      Prints on System.out.

    • println

      public void println(Node node, PrintStream out)
      Prints the tree descending from node with a newline at end.

    • println

      public void println(Node node)
      Prints on System.out.

    • toString

      public String toString(Node node)
      Returns a String representation of the equation.

    • append

      public void append(String s)
      Add a string to buffer. Classes implementing PrintVisitor.PrintRulesI should call this method.
      Parameters:
      s - the string to append
      Since:
      3.4.0

    • addSpecialRule

      public void addSpecialRule(Operator op, PrintVisitor.PrintRulesI rule)
      Adds a special print rule to be added for a given operator.
      Parameters:
      op - the operator the rule applies to
      rule - the print rule to use

    • addSpecialRule

      public void addSpecialRule(String funName, PrintVisitor.PrintRulesI rule)
      Adds a special print rule to be added for a given function.
      Parameters:
      funName - name of function
      rule - the print rule to use

    • addSpecialVarName

      public String addSpecialVarName(String oldName, String newName)
      Allows a replacement for a specific variable name
      Parameters:
      oldName - name of variable to replace
      newName - string to print as replacement

    • printNoBrackets

      public void printNoBrackets(Node node) throws JepException
      Print the node with no brackets.
      Throws:
      JepException

    • printBrackets

      public void printBrackets(Node node) throws JepException
      Print a node surrounded by brackets.
      Throws:
      JepException

    • visitUnary

      protected void visitUnary(ASTOpNode node) throws JepException
      Print a unary operator.
      Throws:
      JepException

    • visitBinary

      protected void visitBinary(ASTOpNode node) throws JepException
      Throws:
      JepException

    • testLeft

      public boolean testLeft(Operator top, Node lhs)
      Test if brackets are necessary around left-hand side.
      Parameters:
      top - The current operator being printed.
      lhs - The node on the left-hand side.
      Returns:
      True if a bracket is necessary, false otherwise.

    • testMid

      public boolean testMid(Operator top, Node mid)
      Test if brackets are needed around a middle argument x + (y) + z
      Parameters:
      top - The current operator being printed.
      mid - The node in the middle of a chain.
      Returns:
      True if a bracket is necessary, false otherwise.

    • testRight

      public boolean testRight(Operator top, Node rhs)
      Tests if brackets are necessary around the RHS child of an operator.
      Parameters:
      top - The operator.
      rhs - The right hand side node.
      Returns:
      True if brackets are necessary, false otherwise.

    • visit

      public Object visit(ASTFunNode node, Object data) throws JepException
      Prints a standard function: fun(arg, arg)
      Specified by:
      visit in interface ParserVisitor
      Throws:
      JepException

    • visit

      public Object visit(ASTOpNode node, Object data) throws JepException
      Specified by:
      visit in interface ParserVisitor
      Throws:
      JepException

    • visit

      public Object visit(ASTVarNode node, Object data) throws JepException
      Specified by:
      visit in interface ParserVisitor
      Throws:
      JepException

    • visit

      public Object visit(ASTConstant node, Object data)
      Specified by:
      visit in interface ParserVisitor

    • formatValue

      public void formatValue(Object val, StringBuffer sb1)
      Appends a formatted versions of val to the string buffer.
      Parameters:
      val - The value to format
      sb1 - The StringBuffer to append to

    • formatValue

      public String formatValue(Object val)
      Returns a formatted version of the value.

    • getMode

      public int getMode()
      Return the current print mode. Note that the mode is a bit field.

    • getMode

      public boolean getMode(int testmode)
      Returns true if the specified testmode is active.
      Parameters:
      testmode - The mode to check.
      Returns:
      True if the specified mode is active.

    • setMode

      public void setMode(int mode, boolean flag)
      Set printing mode. In full bracket mode the brackets each element in the tree will be surrounded by brackets to indicate the tree structure. In the default mode, (full bracket off) the number of brackets is minimized so (x+y)+z will be printed as x+y+z.
      Parameters:
      mode - which flags to change, typically FULL_BRACKET
      flag - whether to switch this mode on or off

    • setNumberFormat

      public void setNumberFormat(NumberFormat format)
      Sets the number format to use. A useful format is a DecimalFormat with minimum fraction digits set to zero. This makes simple powers, like x^2, print nicely. 
      DecimalFormat fmt = new DecimalFormat();
fmt.setMinimumFractionDigits(0);
fmt.setMaximumFractionDigits(15);
jep.getPrintVisitor().setNumberFormat(fmt);
      Parameters:
      format - format to use, if null just uses toString

    • setMaxLen

      public void setMaxLen(int i)
      Sets the maximum length printed per line. If the value is not -1 then the string will be broken into chunks each of which is less than the max length.
      Parameters:
      i - the maximum length

    • getMaxLen

      public int getMaxLen()
      Returns:
      the maximum length printed per line

    • getLightWeightInstance

      public JepComponent getLightWeightInstance()
      Description copied from interface: JepComponent
      Gets a light-weight instance suitable for using in multiple threads.
      Specified by:
      getLightWeightInstance in interface JepComponent
      Returns:
      either a new instance, null or 'this'.

    • getLBracket

      public String getLBracket()
      Get the string for left brackets.

    • setLBracket

      public void setLBracket(String bracket)
      Set the string for left brackets.

    • getRBracket

      public String getRBracket()
      Get the string for right brackets.

    • setRBracket

      public void setRBracket(String bracket)
      Set the string for right brackets.

    • getFunLBracket

      public String getFunLBracket()
      Get the string for left bracket around function arguments.

    • setFunLBracket

      public void setFunLBracket(String funLBracket)
      Set the string for left bracket around function arguments.

    • getFunRBracket

      public String getFunRBracket()
      Get the string for right bracket around function arguments.

    • setFunRBracket

      public void setFunRBracket(String funRBracket)
      Set the string for right bracket around function arguments.

    • getFunArgSep

      public String getFunArgSep()
      Get the string separating function arguments.

    • setFunArgSep

      public void setFunArgSep(String functionArgSep)
      Set the string separating function arguments.