de.up.ling.irtg.codec

Class CodecUtilities

java.lang.Object

de.up.ling.irtg.codec.CodecUtilities

public class CodecUtilities
extends Object

Shared methods that are useful in implementing codecs.

Author:

koller

Constructor Summary

Constructors

Constructor and Description
CodecUtilities()

Method Summary

Modifier and Type	Method and Description
static String	extractName(org.antlr.v4.runtime.RuleContext context, boolean isQuoted) Extracts a name from a given ANTLR rule context.
static Constructor<FeatureFunction>	findFeatureConstructor(String className, int n) Retrieves a constructor for a FeatureFunction.
static Method	findStaticFeatureFactory(String className, String methodName, int n) Retrieves a static factory method by name and number of arguments.
String	gensym(String prefix) Generate a new string with the given prefix.
List<String>	introduceAnonymousStates(ConcreteTreeAutomaton<String> auto, List<String> children, Set<String> states) Normalizes a list of strings by introducing new anonymous states where necessary.
static <I,C extends org.antlr.v4.runtime.ParserRuleContext,O> List<O>	processList(C context, Function<C,List<I>> extractList, Function<I,O> map) Extracts a list of values from an ANTLR context representing a list.
static <O,C extends org.antlr.v4.runtime.ParserRuleContext> Tree<O>	processTree(C context, Function<C,O> label, Function<C,List<C>> children) Extracts a tree of values from an ANTLR context.
static String	stripOuterChars(String s) Removes the first and last character from a string.
static <C extends org.antlr.v4.runtime.ParserRuleContext> double	weight(C weight, Function<C,String> extractStr) Extracts a weight from a string specifying the weight.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CodecUtilities

public CodecUtilities()

Method Detail

stripOuterChars

public static String stripOuterChars(String s)

Removes the first and last character from a string.

Parameters:

s -

Returns:

extractName

public static String extractName(org.antlr.v4.runtime.RuleContext context,
                                 boolean isQuoted)

Extracts a name from a given ANTLR rule context. If the name is surrounded by quotes, the quotes are stripped off. Otherwise, the name is returned verbatim.

Parameters:

context -

isQuoted -

Returns:

introduceAnonymousStates

public List<String> introduceAnonymousStates(ConcreteTreeAutomaton<String> auto,
                                             List<String> children,
                                             Set<String> states)

Normalizes a list of strings by introducing new anonymous states where necessary. For each element of "children", the method checks whether the element is a member of the "states" set. If yes, the element is added to the returned state list. Otherwise, a new anonymous state is added to the automaton "auto", along with a rule that rewrites this state into the element string, and the anonymous state is added to the returned state list.

Parameters:

auto -

children -

states -

Returns:

gensym

public String gensym(String prefix)

Generate a new string with the given prefix. The string is guaranteed to be different form all other gensym'ed strings that came from the same instance of CodecUtilities.

Parameters:

prefix -

Returns:

processList

public static <I,C extends org.antlr.v4.runtime.ParserRuleContext,O> List<O> processList(C context,
                                                                                         Function<C,List<I>> extractList,
                                                                                         Function<I,O> map)

Extracts a list of values from an ANTLR context representing a list. The method first applies the "extractList" function to the given "context", and then applies the "map" function to each value in this list. The method returns the list of values the "map" function returned.

Type Parameters:

I -

C -

O -

Parameters:

context -

extractList -

map -

Returns:

weight

public static <C extends org.antlr.v4.runtime.ParserRuleContext> double weight(C weight,
                                                                               Function<C,String> extractStr)

Extracts a weight from a string specifying the weight. If "weight" is non-null, the method applies the "exactStr" function to extract a string from the "weight" object (e.g., an ANTLR context), strips off the first and last character, and returns the double value represented by the remaining string. Otherwise, the method returns 1.

Type Parameters:

C -

Parameters:

weight -

extractStr -

Returns:

processTree

public static <O,C extends org.antlr.v4.runtime.ParserRuleContext> Tree<O> processTree(C context,
                                                                                       Function<C,O> label,
                                                                                       Function<C,List<C>> children)

Extracts a tree of values from an ANTLR context. The method assumes that the class C of contexts has a tree structure; and that the "children" function extracts the children of a context (as a list of C's) and the "label" function extracts the node label for the context. These methods are then applied recursively to produce a Tree representation of the context.

Type Parameters:

O -

C -

Parameters:

context -

label -

children -

Returns:

findFeatureConstructor

public static Constructor<FeatureFunction> findFeatureConstructor(String className,
                                                                  int n)
                                                           throws ClassNotFoundException,
                                                                  NoSuchMethodException

Retrieves a constructor for a FeatureFunction. The "className" argument specifies the fully qualified name of a subclass of FeatureFunction. The method then looks for a constructor for this class with "n" parameters of type String.

Parameters:

className -

n -

Returns:

Throws:

ClassNotFoundException - no subclass of FeatureFunction could be found

NoSuchMethodException - no constructor with n String parameters could be found

findStaticFeatureFactory

public static Method findStaticFeatureFactory(String className,
                                              String methodName,
                                              int n)
                                       throws ClassNotFoundException,
                                              NoSuchMethodException

Retrieves a static factory method by name and number of arguments. The method looks for a static method className#methodName with n parameters of type String, and returns it.

Parameters:

className -

methodName -

n -

Returns:

Throws:

ClassNotFoundException - the class could not be found

NoSuchMethodException - no method with this name of parameter list could be found