vec_math
Class StringNode

java.lang.Object
  vec_math.Node<String>
      vec_math.StringNode

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

BooleanNode, ExpressionNode

public class StringNode
extends Node<String>
implements Serializable

A node that is parseable from a string. Parentheses are used for changing the normal precedence. The valid operators in a regime must be set explicately with the setValidOperator(java.util.List>) method. For String parsing the following rules must be met.

• Valid operatores are static to allow performance improvements.
• Only unary and binary operators are allowed.
• Valid operators must not be ambiguous in the sense that one operator symbol is the starting sequence of another symbol. The class behaves normally, though, if either the operator type is different (unary to binary) or the precedence of the sub-symboled operator is not lower than the precedence of the super-symboled operator.
• No white spaces are allowed between operators and operands.
• Unary operators must always operate to the right side. E.g. an operator '^2' for squaring is not allowed.
• Binary operators split into subnotes in a way that the portion of the defining string left of the operator defines the sub-node with index number 0 while the part of the string to the right of the operator constitutes the sub-node with index 1.
• Whitespaces or parenthesis at the beginning or end of the defining string are removed prior to parsing.

See Also:

Serialized Form

Field Summary

private int	operatorIndex Position in parse string of node operator.
private static List<Operator<String>>	valid Valid operators.

Constructor Summary

StringNode(String definition)
Constructs a root string node.

StringNode(StringNode parent, String definition, int level)
Defines a fully qualified String node.

Method Summary

private static int	checkParenthesis(String test) Checks if all parenthesis opened are closed again.
private static String	getStripped(String def) Strips the String from leading and trailing whitespaces.
Set<String>	getVariables() It is difficult to assure proper replacement of variables.
protected boolean	isVariable(String sarg) Only strings are considered to be variables.
protected Operator<String>	parseOperator(String def) Parses the input string for the root-level operator with the highest precedence.
protected StringNode[]	parseSub(String def) Parses the String for subnodes.
static String	replaceVariable(String target, String variable, Object map) Returns a string where the occurence of a given variable's name is replaced with the actual value of the variable.
static String	replaceVariable(String target, String variable, Object map, boolean quote) Returns a string where the occurence of a given variable's name is replaced with the actual value of the variable.
static void	setValidOperator(List<Operator<String>> op) Sets the allowed operators.

Methods inherited from class vec_math.Node

equals, getLevel, getParent, getParseSource, getSub, getSubAt, getSubNodeNumber, getTie, getValue, isFinal, isParsed, isRoot, parse, parse, setParse, setParseSource, setSub, setTie, setValue, toString, traceVariable

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

valid

private static List<Operator<String>> valid

Valid operators. Must be set prior to parsing.

operatorIndex

private int operatorIndex

Position in parse string of node operator.

Constructor Detail

StringNode

public StringNode(String definition)

Constructs a root string node.

StringNode

public StringNode(StringNode parent,
                  String definition,
                  int level)

Defines a fully qualified String node. Any subclass of string node must provide a constructor with this format.

See Also:

parseSub(java.lang.String)

Method Detail

setValidOperator

public static void setValidOperator(List<Operator<String>> op)

Sets the allowed operators. This method must be called prior to any call to the parsing methods.

replaceVariable

public static String replaceVariable(String target,
                                     String variable,
                                     Object map)
                              throws ParseException

Returns a string where the occurence of a given variable's name is replaced with the actual value of the variable. This method is used for converting a string like

             sin(height) to sin(0.342956765).
       

Whenever the replacement object is not a string, the object's string representation is used as the replacement. For string objects, however, this string is put within double quotes.

Parameters:

target - The entire string to parse.

variable - The name of the variable as found in the target.

map - The replacement for the variable.

Returns:

The target string with the variable replaced with its value.

Throws:

ParseException - If the variable cannot be found in the target.

replaceVariable

public static String replaceVariable(String target,
                                     String variable,
                                     Object map,
                                     boolean quote)
                              throws ParseException

Returns a string where the occurence of a given variable's name is replaced with the actual value of the variable. This method is used for converting a string like

             sin(height) to sin(0.342956765).
       

Whenever the replacement object is not a string, the object's string representation is used as the replacement. For string objects, however, this string is put within double quotes if the qutoe flag is set.

Parameters:

target - The entire string to parse.

variable - The name of the variable as found in the target.

map - The replacement for the variable.

quote - If true, strings are wrapped in double quotes.

Returns:

The target string with the variable replaced with its value.

Throws:

ParseException - If the variable cannot be found in the target.

isVariable

protected boolean isVariable(String sarg)

Only strings are considered to be variables.

Overrides:

isVariable in class Node<String>

getStripped

private static String getStripped(String def)

Strips the String from leading and trailing whitespaces. Removes root-level parenthesis by re-entrant method.

checkParenthesis

private static int checkParenthesis(String test)

Checks if all parenthesis opened are closed again. Returns zero if successful, otherwise the number of open parenthesis (which can be negative) is returned.

getVariables

public Set<String> getVariables()

It is difficult to assure proper replacement of variables. We do a trick here. First, we collect all variables from the parental class, then we reshovel this in a sorted set, where the longest variable names are first. If we then traverse the set of variables and replace them with some number constant, this should ensure that longest variable names are replaced first.

Overrides:

getVariables in class Node<String>

parseOperator

protected Operator<String> parseOperator(String def)
                                  throws ParseException

Parses the input string for the root-level operator with the highest precedence. If called prior to setValidOperator(java.util.List>) a ParseException is thrown.

Specified by:

parseOperator in class Node<String>

Throws:

ParseException

parseSub

protected StringNode[] parseSub(String def)
                         throws ParseException

Parses the String for subnodes. This method relies that parseOperator(java.lang.String) has been called beforehand which should always be the case in the normal line of execution, guaranteed by the order of method calls in the superclass.

Note that this class is able to produce subnodes of the same class type as itself if the constructor requirement is met.

Specified by:

parseSub in class Node<String>

Throws:

ParseException