International Components for Unicode for Java (icu4j) 74.2 · com.ibm.icu.impl.number.parse.NumberParseMatcher

The core interface implemented by all matchers used for number parsing. Given a string, there should NOT be more than one way to consume the string with the same matcher applied multiple times. If there is, the non-greedy parsing algorithm will be unhappy and may enter an exponential-time loop. For example, consider the "A Matcher" that accepts "any number of As". Given the string "AAAA", there are 2^N = 8 ways to apply the A Matcher to this string: you could have the A Matcher apply 4 times to each character; you could have it apply just once to all the characters; you could have it apply to the first 2 characters and the second 2 characters; and so on. A better version of the "A Matcher" would be for it to accept exactly one A, and allow the algorithm to run it repeatedly to consume a string of multiple As. The A Matcher can implement the Flexible interface below to signal that it can be applied multiple times in a row.

Nested and Inner Type Summary

Modifier and Type	Class and Description
public static interface	NumberParseMatcher.Flexible Matchers can implement the Flexible interface to indicate that they are optional and can be run repeatedly.

Method Summary

Modifier and Type	Method and Description
public boolean	Returns: Whether this matcher thinks there may be more interesting chars beyond the end of the string segment. match(StringSegment The StringSegment to match against. Matches always start at the beginning of the segment. The segment is guaranteed to contain at least one char. segment, ParsedNumber The data structure to store results if the match succeeds. result) Runs this matcher starting at the beginning of the given StringSegment.
public void	postProcess(ParsedNumber The data structure to store results. result) Method called at the end of a parse, after all matchers have failed to consume any more chars.
public boolean	Returns: true if the matcher might be able to match against this segment; false if it definitely will not be able to match. smokeTest(StringSegment The segment to check against. segment) Performs a fast "smoke check" for whether or not this matcher could possibly match against the given string segment.

Method Detail

match	back to summary
public boolean match(StringSegment segment, ParsedNumber result) Runs this matcher starting at the beginning of the given StringSegment. If this matcher finds something interesting in the StringSegment, it should update the offset of the StringSegment corresponding to how many chars were matched. Parameters segment:StringSegment The StringSegment to match against. Matches always start at the beginning of the segment. The segment is guaranteed to contain at least one char. result:ParsedNumber The data structure to store results if the match succeeds. Returns:boolean Whether this matcher thinks there may be more interesting chars beyond the end of the string segment.

match

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public boolean match(StringSegment segment, ParsedNumber result)

Runs this matcher starting at the beginning of the given StringSegment. If this matcher finds something interesting in the StringSegment, it should update the offset of the StringSegment corresponding to how many chars were matched.

Parameters

segment:StringSegment: The StringSegment to match against. Matches always start at the beginning of the segment. The segment is guaranteed to contain at least one char.
result:ParsedNumber: The data structure to store results if the match succeeds.

Returns:boolean

Whether this matcher thinks there may be more interesting chars beyond the end of the string segment.

postProcess	back to summary
public void postProcess(ParsedNumber result) Method called at the end of a parse, after all matchers have failed to consume any more chars. Allows a matcher to make final modifications to the result given the knowledge that no more matches are possible. Parameters result:ParsedNumber The data structure to store results.

postProcess

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public void postProcess(ParsedNumber result)

Method called at the end of a parse, after all matchers have failed to consume any more chars. Allows a matcher to make final modifications to the result given the knowledge that no more matches are possible.

Parameters

result:ParsedNumber: The data structure to store results.

smokeTest back to summary

smokeTest	back to summary
public boolean smokeTest(StringSegment segment) Performs a fast "smoke check" for whether or not this matcher could possibly match against the given string segment. The test should be as fast as possible but also as restrictive as possible. For example, matchers can maintain a UnicodeSet of all code points that count possibly start a match. Matchers should use the `StringSegment#startsWith` method in order to correctly handle case folding. Parameters segment:StringSegment The segment to check against. Returns:boolean true if the matcher might be able to match against this segment; false if it definitely will not be able to match.

public boolean smokeTest(StringSegment segment)

Performs a fast "smoke check" for whether or not this matcher could possibly match against the given string segment. The test should be as fast as possible but also as restrictive as possible. For example, matchers can maintain a UnicodeSet of all code points that count possibly start a match. Matchers should use the StringSegment#startsWith method in order to correctly handle case folding.

Parameters

segment:StringSegment: The segment to check against.

Returns:boolean

true if the matcher might be able to match against this segment; false if it definitely will not be able to match.

public Interface NumberParseMatcher

Nested and Inner Type Summary

Method Summary

Method Detail

public Interface NumberParseMatcher.Flexible