org.apache.commons.codec.language.bm

## Class Rule

- java.lang.Object
- - org.apache.commons.codec.language.bm.Rule

-     public class Rule
      extends Object

  A phoneme rule.

  Rules have a pattern, left context, right context, output phoneme, set of languages for which they apply and a logical flag indicating if all languages must be in play. A rule matches if:

  - the pattern matches at the current position
  - the string up until the beginning of the pattern matches the left context
  - the string from the end of the pattern matches the right context
  - logical is ALL and all languages are in scope; or
  - logical is any other value and at least one language is in scope

  Rules are typically generated by parsing rules resources. In normal use, there will be no need for the user to explicitly construct their own.

  Rules are immutable and thread-safe.

  Rules resources

  Rules are typically loaded from resource files. These are UTF-8 encoded text files. They are systematically named following the pattern:

  > org/apache/commons/codec/language/bm/${NameType#getName}_${RuleType#getName}_${language}.txt

  The format of these resources is the following:

  - Rules: whitespace separated, double-quoted strings. There should be 4 columns to each row, and these will be interpreted as:
    1. pattern
    2. left context
    3. right context
    4. phoneme
  - End-of-line comments: Any occurrence of '//' will cause all text following on that line to be discarded as a comment.
  - Multi-line comments: Any line starting with '/*' will start multi-line commenting mode. This will skip all content until a line ending in '*' and '/' is found.
  - Blank lines: All blank lines will be skipped.
  Since:
    1.6
  Version:
    $Id: Rule.java 1544532 2013-11-22 13:38:35Z ggregory $

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `static class` | `Rule.Phoneme`
    `static interface` | `Rule.PhonemeExpr`
    `static class` | `Rule.PhonemeList`
    `static interface` | `Rule.RPattern` A minimal wrapper around the functionality of Pattern that we use, to allow for alternate implementations.

  - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static String` | `ALL`
    `static Rule.RPattern` | `ALL_STRINGS_RMATCHER`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `Rule(String pattern, String lContext, String rContext, Rule.PhonemeExpr phoneme)` Creates a new rule.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `static List<Rule>` | `getInstance(NameType nameType, RuleType rt, Languages.LanguageSet langs)` Gets rules for a combination of name type, rule type and languages.
    `static List<Rule>` | `getInstance(NameType nameType, RuleType rt, String lang)` Gets rules for a combination of name type, rule type and a single language.
    `static Map<String,List<Rule>>` | `getInstanceMap(NameType nameType, RuleType rt, Languages.LanguageSet langs)` Gets rules for a combination of name type, rule type and languages.
    `static Map<String,List<Rule>>` | `getInstanceMap(NameType nameType, RuleType rt, String lang)` Gets rules for a combination of name type, rule type and a single language.
    `Rule.RPattern` | `getLContext()` Gets the left context.
    `String` | `getPattern()` Gets the pattern.
    `Rule.PhonemeExpr` | `getPhoneme()` Gets the phoneme.
    `Rule.RPattern` | `getRContext()` Gets the right context.
    `boolean` | `patternAndContextMatches(CharSequence input, int i)` Decides if the pattern and context match the input starting at a position.

    - ### Methods inherited from class java.lang.Object

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

- - ### Field Detail

    - #### ALL_STRINGS_RMATCHER

          public static final Rule.RPattern ALL_STRINGS_RMATCHER

    - #### ALL

          public static final String ALL

      See Also:
        Constant Field Values

  - ### Constructor Detail

    - #### Rule

          public Rule(String pattern,
              String lContext,
              String rContext,
              Rule.PhonemeExpr phoneme)

      Creates a new rule.
      Parameters:
        `pattern` - the pattern
        `lContext` - the left context
        `rContext` - the right context
        `phoneme` - the resulting phoneme

  - ### Method Detail

    - #### getInstance

          public static List<Rule> getInstance(NameType nameType,
                               RuleType rt,
                               Languages.LanguageSet langs)

      Gets rules for a combination of name type, rule type and languages.
      Parameters:
        `nameType` - the NameType to consider
        `rt` - the RuleType to consider
        `langs` - the set of languages to consider
      Returns:
        a list of Rules that apply

    - #### getInstance

          public static List<Rule> getInstance(NameType nameType,
                               RuleType rt,
                               String lang)

      Gets rules for a combination of name type, rule type and a single language.
      Parameters:
        `nameType` - the NameType to consider
        `rt` - the RuleType to consider
        `lang` - the language to consider
      Returns:
        a list of Rules that apply

    - #### getInstanceMap

          public static Map<String,List<Rule>> getInstanceMap(NameType nameType,
                                              RuleType rt,
                                              Languages.LanguageSet langs)

      Gets rules for a combination of name type, rule type and languages.
      Parameters:
        `nameType` - the NameType to consider
        `rt` - the RuleType to consider
        `langs` - the set of languages to consider
      Returns:
        a map containing all Rules that apply, grouped by the first character of the rule pattern
      Since:
        1.9

    - #### getInstanceMap

          public static Map<String,List<Rule>> getInstanceMap(NameType nameType,
                                              RuleType rt,
                                              String lang)

      Gets rules for a combination of name type, rule type and a single language.
      Parameters:
        `nameType` - the NameType to consider
        `rt` - the RuleType to consider
        `lang` - the language to consider
      Returns:
        a map containing all Rules that apply, grouped by the first character of the rule pattern
      Since:
        1.9

    - #### getLContext

          public Rule.RPattern getLContext()

      Gets the left context. This is a regular expression that must match to the left of the pattern.
      Returns:
        the left context Pattern

    - #### getPattern

          public String getPattern()

      Gets the pattern. This is a string-literal that must exactly match.
      Returns:
        the pattern

    - #### getPhoneme

          public Rule.PhonemeExpr getPhoneme()

      Gets the phoneme. If the rule matches, this is the phoneme associated with the pattern match.
      Returns:
        the phoneme

    - #### getRContext

          public Rule.RPattern getRContext()

      Gets the right context. This is a regular expression that must match to the right of the pattern.
      Returns:
        the right context Pattern

    - #### patternAndContextMatches

          public boolean patternAndContextMatches(CharSequence input,
                                         int i)

      Decides if the pattern and context match the input starting at a position. It is a match if the `lContext` matches `input` up to `i`, `pattern` matches at i and `rContext` matches from the end of the match of `pattern` to the end of `input`.
      Parameters:
        `input` - the input String
        `i` - the int position within the input
      Returns:
        true if the pattern and left/right context match, false otherwise

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