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# Special cases of A/AN...
my $ORDINAL_AN = qr{\A [aefhilmnorsx] -?th \Z}ix;
my $ORDINAL_A = qr{\A [bcdgjkpqtuvwyz] -?th \Z}ix;
my $EXPLICIT_AN = qr{\A (?: euler | hour(?!i) | heir | honest | hono )}ix;
my $SINGLE_AN = qr{\A [aefhilmnorsx] \Z}ix;
my $SINGLE_A = qr{\A [bcdgjkpqtuvwyz] \Z}ix;
# This pattern matches strings of capitals (i.e. abbreviations) that
# start with a "vowel-sound" consonant followed by another consonant,
# and which are not likely to be real words
# (oh, all right then, it's just magic!)...
my $ABBREV_AN = qr{
\A
(?! FJO | [HLMNS]Y. | RY[EO] | SQU
| ( F[LR]? | [HL] | MN? | N | RH? | S[CHKLMNPTVW]? | X(YL)?) [AEIOU]
)
[FHLMNRSX][A-Z]
}xms;
# This pattern codes the beginnings of all english words begining with a
# 'Y' followed by a consonant. Any other Y-consonant prefix therefore
# implies an abbreviation...
my $INITIAL_Y_AN = qr{\A y (?: b[lor] | cl[ea] | fere | gg | p[ios] | rou | tt)}xi;
sub select_indefinite_article {
my ($word) = @_;
# Handle ordinal forms...
return "a" if $word =~ $ORDINAL_A;
return "an" if $word =~ $ORDINAL_AN;
# Handle special cases...
return "an" if $word =~ $EXPLICIT_AN;
return "an" if $word =~ $SINGLE_AN;
return "a" if $word =~ $SINGLE_A;
# Handle abbreviations...
return "an" if $word =~ $ABBREV_AN;
return "an" if $word =~ /\A [aefhilmnorsx][.-]/xi;
return "a" if $word =~ /\A [a-z][.-]/xi;
# Handle consonants
return "a" if $word =~ /\A [^aeiouy] /xi;
# Handle special vowel-forms
return "a" if $word =~ /\A e [uw] /xi;
return "a" if $word =~ /\A onc?e \b /xi;
return "a" if $word =~ /\A uni (?: [^nmd] | mo) /xi;
return "an" if $word =~ /\A ut[th] /xi;
return "a" if $word =~ /\A u [bcfhjkqrst] [aeiou] /xi;
# Handle special capitals
return "a" if $word =~ /\A U [NK] [AIEO]? /x;
# Handle vowels
return "an" if $word =~ /\A [aeiou]/xi;
# Handle Y... (before certain consonants implies (unnaturalized) "I.." sound)
return "an" if $word =~ $INITIAL_Y_AN;
# Otherwise, guess "A"
return "a";
}
public static String get(String phrase) {
Pattern pattern;
Matcher matcher;
String word, lowercaseWord;
if (phrase.length() == 0) {
return "a";
}
// Getting the first word
pattern = Pattern.compile("(\\w+)\\s*.*");
matcher = pattern.matcher(phrase);
if(matcher.matches() == true) {
word = matcher.group(1);
} else {
return "an";
}
lowercaseWord = word.toLowerCase();
// Specific start of words that should be preceded by 'an'
String [] altCases = { "euler", "heir", "honest", "hono" };
for (String altCase : altCases) {
if (lowercaseWord.startsWith(altCase) == true) {
return "an";
}
}
if (lowercaseWord.startsWith("hour") == true && lowercaseWord.startsWith("houri") == false) {
return "an";
}
// Single letter word which should be preceded by 'an'
if (lowercaseWord.length() == 1) {
if ("aedhilmnorsx".indexOf(lowercaseWord) >= 0) {
return "an";
} else {
return "a";
}
}
// Capital words which should likely be preceded by 'an'
if (word.matches("(?!FJO|[HLMNS]Y.|RY[EO]|SQU|(F[LR]?|[HL]|MN?|N|RH?|S[CHKLMNPTVW]?|X(YL)?)[AEIOU])[FHLMNRSX][A-Z]")) {
return "an";
}
// Special cases where a word that begins with a vowel should be preceded by 'a'
String [] regexes = { "^e[uw]", "^onc?e\\b", "^uni([^nmd]|mo)", "^u[bcfhjkqrst][aeiou]" };
for (String regex : regexes) {
if (lowercaseWord.matches(regex+".*") == true) {
return "a";
}
}
// Special capital words (UK, UN)
if (word.matches("^U[NK][AIEO].*") == true) {
return "a";
} else if (word == word.toUpperCase()) {
if ("aedhilmnorsx".indexOf(lowercaseWord.substring(0, 1)) >= 0) {
return "an";
} else {
return "a";
}
}
// Basic method of words that begin with a vowel being preceded by 'an'
if ("aeiou".indexOf(lowercaseWord.substring(0, 1)) >= 0) {
return "an";
}
// Instances where y followed by specific letters is preceded by 'an'
if (lowercaseWord.matches("^y(b[lor]|cl[ea]|fere|gg|p[ios]|rou|tt).*")) {
return "an";
}
return "a";
}
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