ANTLR 3.5.3 · org.antlr.analysis.Label

Field Summary

Modifier and Type	Field and Description
public static final int	ACTION
public static final int	DOWN
public static final int	EOF
public static final int	EOR_TOKEN_TYPE End of rule token type; imaginary token type used only for local, partial FOLLOW sets to indicate that the local FOLLOW hit the end of rule.
public static final int	EOT End of Token is like EOF for lexer rules.
public static final int	EPSILON
public static final String	EPSILON_STR
public static final int	INVALID
protected int	label The token type or character value; or, signifies special label.
protected IntSet	labelSet A set of token types or character codes if label==SET
public static final int	MAX_CHAR_VALUE
public static final int	MIN_ATOM_VALUE Anything at this value or larger can be considered a simple atom int for easy comparison during analysis only; faux labels are not used during parse time for real token types or char values.
public static final int	MIN_CHAR_VALUE
public static final int	MIN_TOKEN_TYPE tokens and char range overlap; tokens are MIN_TOKEN_TYPE..n
public static final int	NUM_FAUX_LABELS We have labels like EPSILON that are below 0; it's hard to store them in an array with negative index so use this constant as an index shift when accessing arrays based upon token type.
public static final int	SEMPRED label is a semantic predicate; implies label is epsilon also
public static final int	SET label is a set of tokens or char
public static final int	UP

Constructor Summary

Access	Constructor and Description
public	Label(int label)
public	Label(IntSet labelSet) Make a set label

Method Summary

Modifier and Type	Method and Description
public void	add(Label a)
public Object	clone() Overrides java.lang.Object.clone. Creates and returns a copy of this object.
public int	compareTo(Label the object to be compared. o) Implements java.lang.Comparable.compareTo. Compares this object with the specified object for order.
public boolean	equals(Object the reference object with which to compare. o) Overrides java.lang.Object.equals. Indicates whether some other object is "equal to" this one.
public int	getAtom() return the single atom label or INVALID if not a single atom
public SemanticContext	getSemanticContext()
public IntSet	getSet()
public int	hashCode() Overrides java.lang.Object.hashCode. Returns a hash code value for this object.
public static boolean	intersect(Label label, Label edgeLabel)
public boolean	isAction()
public boolean	isAtom()
public boolean	isEpsilon()
public boolean	isSemanticPredicate()
public boolean	isSet()
public boolean	matches(int atom)
public boolean	matches(IntSet set)
public boolean	matches(Label other)
public void	setSet(IntSet set)
public String	toString() Overrides java.lang.Object.toString. Predicates are lists of AST nodes from the NFA created from the grammar, but the same predicate could be cut/paste into multiple places in the grammar.
public String	toString(Grammar g)

Inherited from java.lang.Object:: finalize getClass notify notifyAll wait wait wait

Field Detail

ACTION	back to summary
public static final int ACTION

DOWN	back to summary
public static final int DOWN

EOF	back to summary
public static final int EOF

EOR_TOKEN_TYPE	back to summary
public static final int EOR_TOKEN_TYPE End of rule token type; imaginary token type used only for local, partial FOLLOW sets to indicate that the local FOLLOW hit the end of rule. During error recovery, the local FOLLOW of a token reference may go beyond the end of the rule and have to use FOLLOW(rule). I have to just shift the token types to 2..n rather than 1..n to accommodate this imaginary token in my bitsets. If I didn't use a bitset implementation for runtime sets, I wouldn't need this. EOF is another candidate for a run time token type for parsers. Follow sets are not computed for lexers so we do not have this issue.

EOR_TOKEN_TYPE

back to summary

public static final int EOR_TOKEN_TYPE

End of rule token type; imaginary token type used only for local, partial FOLLOW sets to indicate that the local FOLLOW hit the end of rule. During error recovery, the local FOLLOW of a token reference may go beyond the end of the rule and have to use FOLLOW(rule). I have to just shift the token types to 2..n rather than 1..n to accommodate this imaginary token in my bitsets. If I didn't use a bitset implementation for runtime sets, I wouldn't need this. EOF is another candidate for a run time token type for parsers. Follow sets are not computed for lexers so we do not have this issue.

EOT	back to summary
public static final int EOT End of Token is like EOF for lexer rules. It implies that no more characters are available and that NFA conversion should terminate for this path. For example A : 'a' 'b' \| 'a' ; yields a DFA predictor: o-a->o-b->1 predict alt 1 \| \|-EOT->o predict alt 2 To generate code for EOT, treat it as the "default" path, which implies there is no way to mismatch a char for the state from which the EOT emanates.

EOT

back to summary

public static final int EOT

End of Token is like EOF for lexer rules. It implies that no more characters are available and that NFA conversion should terminate for this path. For example A : 'a' 'b' | 'a' ; yields a DFA predictor: o-a->o-b->1 predict alt 1 | |-EOT->o predict alt 2 To generate code for EOT, treat it as the "default" path, which implies there is no way to mismatch a char for the state from which the EOT emanates.

EPSILON	back to summary
public static final int EPSILON

EPSILON_STR	back to summary
public static final String EPSILON_STR

INVALID	back to summary
public static final int INVALID

label	back to summary
protected int label The token type or character value; or, signifies special label.

labelSet	back to summary
protected IntSet labelSet A set of token types or character codes if label==SET

MAX_CHAR_VALUE	back to summary
public static final int MAX_CHAR_VALUE

MIN_ATOM_VALUE	back to summary
public static final int MIN_ATOM_VALUE Anything at this value or larger can be considered a simple atom int for easy comparison during analysis only; faux labels are not used during parse time for real token types or char values.

MIN_CHAR_VALUE	back to summary
public static final int MIN_CHAR_VALUE

MIN_TOKEN_TYPE	back to summary
public static final int MIN_TOKEN_TYPE tokens and char range overlap; tokens are MIN_TOKEN_TYPE..n

NUM_FAUX_LABELS	back to summary
public static final int NUM_FAUX_LABELS We have labels like EPSILON that are below 0; it's hard to store them in an array with negative index so use this constant as an index shift when accessing arrays based upon token type. If real token type is i, then array index would be NUM_FAUX_LABELS + i.

SEMPRED	back to summary
public static final int SEMPRED label is a semantic predicate; implies label is epsilon also

SET	back to summary
public static final int SET label is a set of tokens or char

UP	back to summary
public static final int UP

Constructor Detail

Label	back to summary
public Label(int label)

Label	back to summary
public Label(IntSet labelSet) Make a set label

Method Detail

add	back to summary
public void add(Label a)

clone back to summary

clone	back to summary
public Object clone() Overrides java.lang.Object.clone. Doc from java.lang.Object.clone. Creates and returns a copy of this object. The precise meaning of "copy" may depend on the class of the object. The general intent is that, for any object `x`, the expression: x.clone() != x will be true, and that the expression: x.clone().getClass() == x.getClass() will be `true`, but these are not absolute requirements. While it is typically the case that: x.clone().equals(x) will be `true`, this is not an absolute requirement. By convention, the returned object should be obtained by calling `super.clone`. If a class and all of its superclasses (except `Object`) obey this convention, it will be the case that `x.clone().getClass() == x.getClass()`. By convention, the object returned by this method should be independent of this object (which is being cloned). To achieve this independence, it may be necessary to modify one or more fields of the object returned by `super.clone` before returning it. Typically, this means copying any mutable objects that comprise the internal "deep structure" of the object being cloned and replacing the references to these objects with references to the copies. If a class contains only primitive fields or references to immutable objects, then it is usually the case that no fields in the object returned by `super.clone` need to be modified. Returns:Object a clone of this instance. Annotations @Override

public Object clone()

Overrides java.lang.Object.clone.

Doc from java.lang.Object.clone.

Creates and returns a copy of this object. The precise meaning of "copy" may depend on the class of the object. The general intent is that, for any object x, the expression:

x.clone() != x

will be true, and that the expression:

x.clone().getClass() == x.getClass()

will be true, but these are not absolute requirements. While it is typically the case that:

x.clone().equals(x)

will be true, this is not an absolute requirement.

By convention, the returned object should be obtained by calling super.clone. If a class and all of its superclasses (except Object) obey this convention, it will be the case that x.clone().getClass() == x.getClass().

By convention, the object returned by this method should be independent of this object (which is being cloned). To achieve this independence, it may be necessary to modify one or more fields of the object returned by super.clone before returning it. Typically, this means copying any mutable objects that comprise the internal "deep structure" of the object being cloned and replacing the references to these objects with references to the copies. If a class contains only primitive fields or references to immutable objects, then it is usually the case that no fields in the object returned by super.clone need to be modified.

Returns:Object

a clone of this instance.

Annotations

@Override

compareTo back to summary

compareTo	back to summary
public int compareTo(Label o) Implements java.lang.Comparable.compareTo. Doc from java.lang.Comparable.compareTo. Compares this object with the specified object for order. Returns a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object. The implementor must ensure `signum(x.compareTo(y)) == -signum(y.compareTo(x))` for all `x` and `y`. (This implies that `x.compareTo(y)` must throw an exception if and only if `y.compareTo(x)` throws an exception.) The implementor must also ensure that the relation is transitive: `(x.compareTo(y) > 0 && y.compareTo(z) > 0)` implies `x.compareTo(z) > 0`. Finally, the implementor must ensure that `x.compareTo(y)==0` implies that `signum(x.compareTo(z)) == signum(y.compareTo(z))`, for all `z`. Parameters o:Label the object to be compared. Returns:int a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object. Annotations @Override

public int compareTo(Label o)

Implements java.lang.Comparable.compareTo.

Doc from java.lang.Comparable.compareTo.

Compares this object with the specified object for order. Returns a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object.

The implementor must ensure signum(x.compareTo(y)) == -signum(y.compareTo(x)) for all x and y. (This implies that x.compareTo(y) must throw an exception if and only if y.compareTo(x) throws an exception.)

The implementor must also ensure that the relation is transitive: (x.compareTo(y) > 0 && y.compareTo(z) > 0) implies x.compareTo(z) > 0.

Finally, the implementor must ensure that x.compareTo(y)==0 implies that signum(x.compareTo(z)) == signum(y.compareTo(z)), for all z.

Parameters

o:Label: the object to be compared.

Returns:int

a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object.

Annotations

@Override

equals back to summary

equals	back to summary
public boolean equals(Object o) Overrides java.lang.Object.equals. Doc from java.lang.Object.equals. Indicates whether some other object is "equal to" this one. The `equals` method implements an equivalence relation on non-null object references: It is reflexive: for any non-null reference value `x`, `x.equals(x)` should return `true`. It is symmetric: for any non-null reference values `x` and `y`, `x.equals(y)` should return `true` if and only if `y.equals(x)` returns `true`. It is transitive: for any non-null reference values `x`, `y`, and `z`, if `x.equals(y)` returns `true` and `y.equals(z)` returns `true`, then `x.equals(z)` should return `true`. It is consistent: for any non-null reference values `x` and `y`, multiple invocations of `x.equals(y)` consistently return `true` or consistently return `false`, provided no information used in `equals` comparisons on the objects is modified. For any non-null reference value `x`, `x.equals(null)` should return `false`. An equivalence relation partitions the elements it operates on into equivalence classes; all the members of an equivalence class are equal to each other. Members of an equivalence class are substitutable for each other, at least for some purposes. Parameters o:Object the reference object with which to compare. Returns:boolean `true` if this object is the same as the obj argument; `false` otherwise. Annotations @Override

public boolean equals(Object o)

Overrides java.lang.Object.equals.

Doc from java.lang.Object.equals.

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

It is reflexive: for any non-null reference value x, x.equals(x) should return true.
It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
For any non-null reference value x, x.equals(null) should return false.

An equivalence relation partitions the elements it operates on into equivalence classes; all the members of an equivalence class are equal to each other. Members of an equivalence class are substitutable for each other, at least for some purposes.

Parameters

o:Object: the reference object with which to compare.

Returns:boolean

true if this object is the same as the obj argument; false otherwise.

Annotations

@Override

getAtom	back to summary
public int getAtom() return the single atom label or INVALID if not a single atom

getSemanticContext	back to summary
public SemanticContext getSemanticContext()

getSet	back to summary
public IntSet getSet()

hashCode back to summary

hashCode	back to summary
public int hashCode() Overrides java.lang.Object.hashCode. Doc from java.lang.Object.hashCode. Returns a hash code value for this object. This method is supported for the benefit of hash tables such as those provided by `java.util.HashMap`. The general contract of `hashCode` is: Whenever it is invoked on the same object more than once during an execution of a Java application, the `hashCode` method must consistently return the same integer, provided no information used in `equals` comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application. If two objects are equal according to the `equals` method, then calling the `hashCode` method on each of the two objects must produce the same integer result. It is not required that if two objects are unequal according to the `equals` method, then calling the `hashCode` method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables. Returns:int a hash code value for this object Annotations @Override

public int hashCode()

Overrides java.lang.Object.hashCode.

Doc from java.lang.Object.hashCode.

Returns a hash code value for this object. This method is supported for the benefit of hash tables such as those provided by java.util.HashMap.

The general contract of hashCode is:

Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
If two objects are equal according to the equals method, then calling the hashCode method on each of the two objects must produce the same integer result.
It is not required that if two objects are unequal according to the equals method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.

Returns:int

a hash code value for this object

Annotations

@Override

intersect	back to summary
public static boolean intersect(Label label, Label edgeLabel)

isAction	back to summary
public boolean isAction()

isAtom	back to summary
public boolean isAtom()

isEpsilon	back to summary
public boolean isEpsilon()

isSemanticPredicate	back to summary
public boolean isSemanticPredicate()

isSet	back to summary
public boolean isSet()

matches	back to summary
public boolean matches(int atom)

matches	back to summary
public boolean matches(IntSet set)

matches	back to summary
public boolean matches(Label other)

setSet	back to summary
public void setSet(IntSet set)

toString	back to summary
public String toString() Overrides java.lang.Object.toString. Predicates are lists of AST nodes from the NFA created from the grammar, but the same predicate could be cut/paste into multiple places in the grammar. I must compare the text of all the predicates to truly answer whether {p1,p2} .equals {p1,p2}. Unfortunately, I cannot rely on the AST.equals() to work properly so I must do a brute force O(n^2) nested traversal of the Set doing a String compare. At this point, Labels are not compared for equals when they are predicates, but here's the code for future use. Returns:String Doc from java.lang.Object.toString. a string representation of the object Annotations @Override

toString

back to summary

public String toString()

Overrides java.lang.Object.toString.

Predicates are lists of AST nodes from the NFA created from the grammar, but the same predicate could be cut/paste into multiple places in the grammar. I must compare the text of all the predicates to truly answer whether {p1,p2} .equals {p1,p2}. Unfortunately, I cannot rely on the AST.equals() to work properly so I must do a brute force O(n^2) nested traversal of the Set doing a String compare. At this point, Labels are not compared for equals when they are predicates, but here's the code for future use.

Returns:String

Doc from java.lang.Object.toString.

a string representation of the object

Annotations

@Override

toString	back to summary
public String toString(Grammar g)

public Class Label

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