hunspell - format of Hunspell dictionaries and affix files
hunspell(4) Hunspell requires two files to define the way a language is being spell checked: a dictionary file containing words and applicable flags, and an affix file that specifies how these flags wil controll spell checking. An optional file is the personal dictionary file.
A dictionary file (*.dic) contains a list of words, one per line. The first line of the dictionaries (except personal dictionaries) contains the approximate word count (for optimal hash memory size). Each word may optionally be followed by a slash ("/") and one or more flags, which represents the word attributes, for example affixes. Note: Dictionary words can contain also slashes when escaped like "" syntax.
Personal dictionary file
Personal dictionaries are simple word lists. Asterisk at the first character position signs prohibition. A second word separated by a slash sets the affixation. foo Foo/Simpson *bar In this example, "foo" and "Foo" are personal words, plus Foo will be recognized with affixes of Simpson (Foo's etc.) and bar is a forbidden word.
Dictionary file: 3 hello try/B work/AB The flags B and A specify attributes of these words. Affix file: SET UTF-8 TRY esianrtolcdugmphbyfvkwzESIANRTOLCDUGMPHBYFVKWZ' REP 2 REP f ph REP ph f PFX A Y 1 PFX A 0 re . SFX B Y 2 SFX B 0 ed [^y] SFX B y ied y In the affix file, prefix A and suffix B have been defined. Flag A defines a `re-' prefix. Class B defines two `-ed' suffixes. First B suffix can be added to a word if the last character of the word isn't `y'. Second suffix can be added to the words terminated with an `y'. All accepted words with this dictionary and affix combination are: "hello", "try", "tried", "work", "worked", "rework", "reworked".
AFFIX FILE GENERAL OPTIONS
Hunspell source distribution contains more than 80 examples for option usage. SET encoding Set character encoding of words and morphemes in affix and dic- tionary files. Possible values: UTF-8, ISO8859-1 - ISO8859-10, ISO8859-13 - ISO8859-15, KOI8-R, KOI8-U, microsoft-cp1251, ISCII-DEVANAGARI. SET UTF-8 FLAG value Set flag type. Default type is the extended ASCII (8-bit) char- acter. `UTF-8' parameter sets UTF-8 encoded Unicode character flags. The `long' value sets the double extended ASCII charac- ter flag type, the `num' sets the decimal number flag type. Dec- imal flags numbered from 1 to 65000, and in flag fields are sep- arated by comma. BUG: UTF-8 flag type doesn't work on ARM plat- form. FLAG long COMPLEXPREFIXES Set twofold prefix stripping (but single suffix stripping) eg. for morphologically complex languages with right-to-left writing system. LANG langcode Set language code for language specific functions of Hunspell. Use it to activate special casing of Azeri (LANG az) and Turkish (LANG tr). IGNORE characters Sets characters to ignore dictionary words, affixes and input words. Useful for optional characters, as Arabic (harakat) or Hebrew (niqqud) diacritical marks (see tests/ignore.* test dic- tionary in Hunspell distribution). AF number_of_flag_vector_aliases AF flag_vector Hunspell can substitute affix flag sets with ordinal numbers in affix rules (alias compression, see makealias tool). First exam- ple with alias compression: 3 hello try/1 work/2 AF definitions in the affix file: AF 2 AF A AF AB It is equivalent of the following dic file: 3 hello try/A work/AB See also tests/alias* examples of the source distribution. Note I: If affix file contains the FLAG parameter, define it before the AF definitions. Note II: Use makealias utility in Hunspell distribution to compress aff and dic files. AM number_of_morphological_aliases AM morphological_fields Hunspell can substitute also morphological data with ordinal numbers in affix rules (alias compression). See tests/alias* examples.
AFFIX FILE OPTIONS FOR SUGGESTION
Suggestion parameters can optimize the default n-gram (similarity search in the dictionary words based on the common 1, 2, 3, 4-character length common character-sequences), character swap and deletion sugges- tions of Hunspell. REP is suggested to fix the typical and especially bad language specific bugs, because the REP suggestions have the high- est priority in the suggestion list. PHONE is for languages with not pronunciation based orthography. KEY characters_separated_by_vertical_line_optionally Hunspell searches and suggests words with one different charac- ter replaced by a neighbor KEY character. Not neighbor charac- ters in KEY string separated by vertical line characters. Sug- gested KEY parameters for QWERTY and Dvorak keyboard layouts: KEY qwertyuiop|asdfghjkl|zxcvbnm KEY pyfgcrl|aeouidhtns|qjkxbmwvz Using the first QWERTY layout, Hunspell suggests "nude" and "node" for "*nide". A character may have more neighbors, too: KEY qwertzuop|yxcvbnm|qaw|say|wse|dsx|sy|edr|fdc|dx|rft|gfv|fc|tgz|hgb|gv|zhu|jhn|hb|uji|kjm|jn|iko|lkm TRY characters Hunspell can suggest right word forms, when they differ from the bad input word by one TRY character. The parameter of TRY is case sensitive. NOSUGGEST flag Words signed with NOSUGGEST flag are not suggested (but still accepted when typed correctly). Proposed flag for vulgar and obscene words (see also SUBSTANDARD). MAXCPDSUGS num Set max. number of suggested compound words generated by com- pound rules. The number of the suggested compound words may be greater from the same 1-character distance type. MAXNGRAMSUGS num Set max. number of n-gram suggestions. Value 0 switches off the n-gram suggestions (see also MAXDIFF). MAXDIFF [0-10] Set the similarity factor for the n-gram based suggestions (5 = default value; 0 = fewer n-gram suggestions, but min. 1; 10 = MAXNGRAMSUGS n-gram suggestions). ONLYMAXDIFF Remove all bad n-gram suggestions (default mode keeps one, see MAXDIFF). NOSPLITSUGS Disable word suggestions with spaces. SUGSWITHDOTS Add dot(s) to suggestions, if input word terminates in dot(s). (Not for OpenOffice.org dictionaries, because OpenOffice.org has an automatic dot expansion mechanism.) REP number_of_replacement_definitions REP what replacement This table specifies modifications to try first. First REP is the header of this table and one or more REP data line are fol- lowing it. With this table, Hunspell can suggest the right forms for the typical spelling mistakes when the incorrect form differs by more than 1 letter from the right form. The search string supports the regex boundary signs (^ and $). For example a possible English replacement table definition to handle mis- spelled consonants: REP 5 REP f ph REP ph f REP tion$ shun REP ^cooccurr co-occurr REP ^alot$ a_lot Note I: It's very useful to define replacements for the most typical one-character mistakes, too: with REP you can add higher priority to a subset of the TRY suggestions (suggestion list begins with the REP sug- gestions). Note II: Suggesting separated words, specify spaces with underlines: REP 1 REP onetwothree one_two_three Note III: Replacement table can be used for a stricter compound word checking with the option CHECKCOMPOUNDREP. MAP number_of_map_definitions MAP string_of_related_chars_or_parenthesized_character_sequences We can define language-dependent information on characters and character sequences that should be considered related (i.e. nearer than other chars not in the set) in the affix file (.aff) by a map table. With this table, Hunspell can suggest the right forms for words, which incorrectly choose the wrong letter or letter groups from a related set more than once in a word (see REP). For example a possible mapping could be for the German umlauted A1/4 versus the regular u; the word FrA1/4hstA1/4ck really should be written with umlauted u's and not regular ones MAP 1 MAP uA1/4 Use parenthesized groups for character sequences (eg. for composed Uni- code characters): MAP 3 MAP A(ss) (character sequence) MAP i~(fi) ("fi" compatibility characters for Unicode fi ligature) MAP (A3IL)o (composed Unicode character: A3 with bottom dot) PHONE number_of_phone_definitions PHONE what replacement PHONE uses a table-driven phonetic transcription algorithm bor- rowed from Aspell. It is useful for languages with not pronunci- ation based orthography. You can add a full alphabet conversion and other rules for conversion of special letter sequences. For detailed documentation see http://aspell.net/man-html/Phonetic- Code.html. Note: Multibyte UTF-8 characters have not worked with bracket expression yet. Dash expression has signed bytes and not UTF-8 characters yet. WARN flag This flag is for rare words, wich are also often spelling mis- takes, see option -r of command line Hunspell and FORBIDWARN. FORBIDWARN Words with flag WARN aren't accepted by the spell checker using this parameter.
OPTIONS FOR COMPOUNDING
BREAK number_of_break_definitions BREAK character_or_character_sequence Define new break points for breaking words and checking word parts separately. Use ^ and $ to delete characters at end and start of the word. Rationale: useful for compounding with join- ing character or strings (for example, hyphen in English and German or hyphen and n-dash in Hungarian). Dashes are often bad break points for tokenization, because compounds with dashes may contain not valid parts, too.) With BREAK, Hunspell can check both side of these compounds, breaking the words at dashes and n-dashes: BREAK 2 BREAK - BREAK -- # n-dash Breaking are recursive, so foo-bar, bar-foo and foo-foo--bar-bar would be valid compounds. Note: The default word break of Hunspell is equiv- alent of the following BREAK definition: BREAK 3 BREAK - BREAK ^- BREAK -$ Hunspell doesn't accept the "-word" and "word-" forms by this BREAK definition: BREAK 1 BREAK - Switching off the default values: BREAK 0 Note II: COMPOUNDRULE is better for handling dashes and other compound joining characters or character strings. Use BREAK, if you want to check words with dashes or other joining characters and there is no time or possibility to describe precise compound rules with COM- POUNDRULE (COMPOUNDRULE handles only the suffixation of the last word part of a compound word). Note III: For command line spell checking of words with extra charac- ters, set WORDCHARS parameters: WORDCHARS --- (see tests/break.*) exam- ple COMPOUNDRULE number_of_compound_definitions COMPOUNDRULE compound_pattern Define custom compound patterns with a regex-like syntax. The first COMPOUNDRULE is a header with the number of the following COMPOUNDRULE definitions. Compound patterns consist compound flags, parentheses, star and question mark meta characters. A flag followed by a `*' matches a word sequence of 0 or more matches of words signed with this compound flag. A flag fol- lowed by a `?' matches a word sequence of 0 or 1 matches of a word signed with this compound flag. See tests/compound*.* examples. Note: en_US dictionary of OpenOffice.org uses COMPOUNDRULE for ordinal number recognition (1st, 2nd, 11th, 12th, 22nd, 112th, 1000122nd etc.). Note II: In the case of long and numerical flag types use only parenthesized flags: (1500)*(2000)? Note III: COMPOUNDRULE flags work completely separately from the compounding mechanisme using COMPOUNDFLAG, COMPOUNDBEGIN, etc. compound flags. (Use these flags on different enhtries for words). COMPOUNDMIN num Minimum length of words used for compounding. Default value is 3 letters. COMPOUNDFLAG flag Words signed with COMPOUNDFLAG may be in compound words (except when word shorter than COMPOUNDMIN). Affixes with COMPOUNDFLAG also permits compounding of affixed words. COMPOUNDBEGIN flag Words signed with COMPOUNDBEGIN (or with a signed affix) may be first elements in compound words. COMPOUNDLAST flag Words signed with COMPOUNDLAST (or with a signed affix) may be last elements in compound words. COMPOUNDMIDDLE flag Words signed with COMPOUNDMIDDLE (or with a signed affix) may be middle elements in compound words. ONLYINCOMPOUND flag Suffixes signed with ONLYINCOMPOUND flag may be only inside of compounds (Fuge-elements in German, fogemorphemes in Swedish). ONLYINCOMPOUND flag works also with words (see tests/onlyincom- pound.*). Note: also valuable to flag compounding parts which are not correct as a word by itself. COMPOUNDPERMITFLAG flag Prefixes are allowed at the beginning of compounds, suffixes are allowed at the end of compounds by default. Affixes with COM- POUNDPERMITFLAG may be inside of compounds. COMPOUNDFORBIDFLAG flag Suffixes with this flag forbid compounding of the affixed word. COMPOUNDROOT flag COMPOUNDROOT flag signs the compounds in the dictionary (Now it is used only in the Hungarian language specific code). COMPOUNDWORDMAX number Set maximum word count in a compound word. (Default is unlim- ited.) CHECKCOMPOUNDDUP Forbid word duplication in compounds (e.g. foofoo). CHECKCOMPOUNDREP Forbid compounding, if the (usually bad) compound word may be a non compound word with a REP fault. Useful for languages with `compound friendly' orthography. CHECKCOMPOUNDCASE Forbid upper case characters at word boundaries in compounds. CHECKCOMPOUNDTRIPLE Forbid compounding, if compound word contains triple repeating letters (e.g. foo|ox or xo|oof). Bug: missing multi-byte charac- ter support in UTF-8 encoding (works only for 7-bit ASCII char- acters). SIMPLIFIEDTRIPLE Allow simplified 2-letter forms of the compounds forbidden by CHECKCOMPOUNDTRIPLE. It's useful for Swedish and Norwegian (and for the old German orthography: Schiff|fahrt -> Schiffahrt). CHECKCOMPOUNDPATTERN number_of_checkcompoundpattern_definitions CHECKCOMPOUNDPATTERN endchars[/flag] beginchars[/flag] [replacement] Forbid compounding, if the first word in the compound ends with endchars, and next word begins with beginchars and (optionally) they have the requested flags. The optional replacement parame- ter allows simplified compound form. The special "endchars" pattern 0 (zero) limits the rule to the unmodified stems (stems and stems with zero affixes): CHECKCOMPOUNDPATTERN 0/x /y Note: COMPOUNDMIN doesn't work correctly with the compound word alter- nation, so it may need to set COMPOUNDMIN to lower value. FORCEUCASE flag Last word part of a compound with flag FORCEUCASE forces capi- talization of the whole compound word. Eg. Dutch word "straat" (street) with FORCEUCASE flags will allowed only in capitalized compound forms, according to the Dutch spelling rules for proper names. COMPOUNDSYLLABLE max_syllable vowels Need for special compounding rules in Hungarian. First parame- ter is the maximum syllable number, that may be in a compound, if words in compounds are more than COMPOUNDWORDMAX. Second parameter is the list of vowels (for calculating syllables). SYLLABLENUM flags Need for special compounding rules in Hungarian.
AFFIX FILE OPTIONS FOR AFFIX CREATION
PFX flag cross_product number PFX flag stripping prefix [condition [morphological_fields...]] SFX flag cross_product number SFX flag stripping suffix [condition [morphological_fields...]] An affix is either a prefix or a suffix attached to root words to make other words. We can define affix classes with arbitrary number affix rules. Affix classes are signed with affix flags. The first line of an affix class definition is the header. The fields of an affix class header: (0) Option name (PFX or SFX) (1) Flag (name of the affix class) (2) Cross product (permission to combine prefixes and suffixes). Possible values: Y (yes) or N (no) (3) Line count of the following rules. Fields of an affix rules: (0) Option name (1) Flag (2) stripping characters from beginning (at prefix rules) or end (at suffix rules) of the word (3) affix (optionally with flags of continuation classes, sepa- rated by a slash) (4) condition. Zero stripping or affix are indicated by zero. Zero condition is indicated by dot. Condition is a simplified, regular expres- sion-like pattern, which must be met before the affix can be applied. (Dot signs an arbitrary character. Characters in braces sign an arbitrary character from the character subset. Dash hasn't got special meaning, but circumflex (^) next the first brace sets the complementer character set.) (5) Optional morphological fields separated by spaces or tabula- tors.
AFFIX FILE OTHER OPTIONS
CIRCUMFIX flag Affixes signed with CIRCUMFIX flag may be on a word when this word also has a prefix with CIRCUMFIX flag and vice versa (see circumfix.* test files in the source distribution). FORBIDDENWORD flag This flag signs forbidden word form. Because affixed forms are also forbidden, we can subtract a subset from set of the accepted affixed and compound words. Note: usefull to forbid erroneous words, generated by the compounding mechanism. FULLSTRIP With FULLSTRIP, affix rules can strip full words, not only one less characters, before adding the affixes, see fullstrip.* test files in the source distribution). Note: conditions may be word length without FULLSTRIP, too. KEEPCASE flag Forbid uppercased and capitalized forms of words signed with KEEPCASE flags. Useful for special orthographies (measurements and currency often keep their case in uppercased texts) and writing systems (e.g. keeping lower case of IPA characters). Also valuable for words erroneously written in the wrong case. Note: With CHECKSHARPS declaration, words with sharp s and KEEP- CASE flag may be capitalized and uppercased, but uppercased forms of these words may not contain sharp s, only SS. See ger- mancompounding example in the tests directory of the Hunspell distribution. ICONV number_of_ICONV_definitions ICONV pattern pattern2 Define input conversion table. Note: useful to convert one type of quote to another one, or change ligature. OCONV number_of_OCONV_definitions OCONV pattern pattern2 Define output conversion table. LEMMA_PRESENT flag Deprecated. Use "st:" field instead of LEMMA_PRESENT. NEEDAFFIX flag This flag signs virtual stems in the dictionary, words only valid when affixed. Except, if the dictionary word has a homonym or a zero affix. NEEDAFFIX works also with prefixes and prefix + suffix combinations (see tests/pseudoroot5.*). PSEUDOROOT flag Deprecated. (Former name of the NEEDAFFIX option.) SUBSTANDARD flag SUBSTANDARD flag signs affix rules and dictionary words (allo- morphs) not used in morphological generation (and in suggestion in the future versions). See also NOSUGGEST. WORDCHARS characters WORDCHARS extends tokenizer of Hunspell command line interface with additional word character. For example, dot, dash, n-dash, numbers, percent sign are word character in Hungarian. CHECKSHARPS SS letter pair in uppercased (German) words may be upper case sharp s (A). Hunspell can handle this special casing with the CHECKSHARPS declaration (see also KEEPCASE flag and tests/ger- mancompounding example) in both spelling and suggestion.
Hunspell's dictionary items and affix rules may have optional space or tabulator separated morphological description fields, started with 3-character (two letters and a colon) field IDs: word/flags po:noun is:nom Example: We define a simple resource with morphological informations, a derivative suffix (ds:) and a part of speech category (po:): Affix file: SFX X Y 1 SFX X 0 able . ds:able Dictionary file: drink/X po:verb Test file: drink drinkable Test: $ analyze test.aff test.dic test.txt > drink analyze(drink) = po:verb stem(drink) = po:verb > drinkable analyze(drinkable) = po:verb ds:able stem(drinkable) = drinkable You can see in the example, that the analyzer concatenates the morpho- logical fields in item and arrangement style.
Optional data fields
Default morphological and other IDs (used in suggestion, stemming and morphological generation): ph: Alternative transliteration for better suggestion. It's useful for words with foreign pronunciation. (Dictionary based phonetic suggestion.) For example: Marseille ph:maarsayl st: Stem. Optional: default stem is the dictionary item in morpho- logical analysis. Stem field is useful for virtual stems (dic- tionary words with NEEDAFFIX flag) and morphological exceptions instead of new, single used morphological rules. feet st:foot is:plural mice st:mouse is:plural teeth st:tooth is:plural Word forms with multiple stems need multiple dictionary items: lay po:verb st:lie is:past_2 lay po:verb is:present lay po:noun al: Allomorph(s). A dictionary item is the stem of its allomorphs. Morphological generation needs stem, allomorph and affix fields. sing al:sang al:sung sang st:sing sung st:sing po: Part of speech category. ds: Derivational suffix(es). Stemming doesn't remove derivational suffixes. Morphological generation depends on the order of the suffix fields. In affix rules: SFX Y Y 1 SFX Y 0 ly . ds:ly_adj In the dictionary: ably st:able ds:ly_adj able al:ably is: Inflectional suffix(es). All inflectional suffixes are removed by stemming. Morphological generation depends on the order of the suffix fields. feet st:foot is:plural ts: Terminal suffix(es). Terminal suffix fields are inflectional suffix fields "removed" by additional (not terminal) suffixes. Useful for zero morphemes and affixes removed by splitting rules. work/D ts:present SFX D Y 2 SFX D 0 ed . is:past_1 SFX D 0 ed . is:past_2 Typical example of the terminal suffix is the zero morpheme of the nom- inative case. sp: Surface prefix. Temporary solution for adding prefixes to the stems and generated word forms. See tests/morph.* example. pa: Parts of the compound words. Output fields of morphological analysis for stemming. dp: Planned: derivational prefix. ip: Planned: inflectional prefix. tp: Planned: terminal prefix.
Twofold suffix stripping
Ispell's original algorithm strips only one suffix. Hunspell can strip another one yet (or a plus prefix in COMPLEXPREFIXES mode). The twofold suffix stripping is a significant improvement in handling of immense number of suffixes, that characterize agglutinative lan- guages. A second `s' suffix (affix class Y) will be the continuation class of the suffix `able' in the following example: SFX Y Y 1 SFX Y 0 s . SFX X Y 1 SFX X 0 able/Y . Dictionary file: drink/X Test file: drink drinkable drinkables Test: $ hunspell -m -d test <test.txt drink st:drink drinkable st:drink fl:X drinkables st:drink fl:X fl:Y Theoretically with the twofold suffix stripping needs only the square root of the number of suffix rules, compared with a Hunspell implemen- tation. In our practice, we could have elaborated the Hungarian inflec- tional morphology with twofold suffix stripping.
Extended affix classes
Hunspell can handle more than 65000 affix classes. There are three new syntax for giving flags in affix and dictionary files. FLAG long command sets 2-character flags: FLAG long SFX Y1 Y 1 SFX Y1 0 s 1 Dictionary record with the Y1, Z3, F? flags: foo/Y1Z3F? FLAG num command sets numerical flags separated by comma: FLAG num SFX 65000 Y 1 SFX 65000 0 s 1 Dictionary example: foo/65000,12,2756 The third one is the Unicode character flags.
Hunspell's dictionary can contain repeating elements that are homonyms: work/A po:verb work/B po:noun An affix file: SFX A Y 1 SFX A 0 s . sf:sg3 SFX B Y 1 SFX B 0 s . is:plur Test file: works Test: $ hunspell -d test -m <testwords work st:work po:verb is:sg3 work st:work po:noun is:plur This feature also gives a way to forbid illegal prefix/suffix combina- tions.
An interesting side-effect of multi-step stripping is, that the appro- priate treatment of circumfixes now comes for free. For instance, in Hungarian, superlatives are formed by simultaneous prefixation of leg- and suffixation of -bb to the adjective base. A problem with the one- level architecture is that there is no way to render lexical licensing of particular prefixes and suffixes interdependent, and therefore incorrect forms are recognized as valid, i.e. *legv~<i>A(C)n = leg + v~<i>A(C)n `old'. Until the introduction of clusters, a special treatment of the superlative had to be hardwired in the earlier HunSpell code. This may have been legitimate for a single case, but in fact prefix--suffix dependences are ubiquitous in category-changing derivational patterns (cf. English payable, non-payable but *non-pay or drinkable, undrink- able but *undrink). In simple words, here, the prefix un- is legitimate only if the base drink is suffixed with -able. If both these patters are handled by on-line affix rules and affix rules are checked against the base only, there is no way to express this dependency and the sys- tem will necessarily over- or undergenerate. In next example, suffix class R have got a prefix `continuation' class (class P). PFX P Y 1 PFX P 0 un . [prefix_un]+ SFX S Y 1 SFX S 0 s . +PL SFX Q Y 1 SFX Q 0 s . +3SGV SFX R Y 1 SFX R 0 able/PS . +DER_V_ADJ_ABLE Dictionary: 2 drink/RQ [verb] drink/S [noun] Morphological analysis: > drink drink[verb] drink[noun] > drinks drink[verb]+3SGV drink[noun]+PL > drinkable drink[verb]+DER_V_ADJ_ABLE > drinkables drink[verb]+DER_V_ADJ_ABLE+PL > undrinkable [prefix_un]+drink[verb]+DER_V_ADJ_ABLE > undrinkables [prefix_un]+drink[verb]+DER_V_ADJ_ABLE+PL > undrink Unknown word. > undrinks Unknown word.
Conditional affixes implemented by a continuation class are not enough for circumfixes, because a circumfix is one affix in morphology. We also need CIRCUMFIX option for correct morphological analysis. # circumfixes: ~ obligate prefix/suffix combinations # superlative in Hungarian: leg- (prefix) AND -bb (suffix) # nagy, nagyobb, legnagyobb, legeslegnagyobb # (great, greater, greatest, most greatest) CIRCUMFIX X PFX A Y 1 PFX A 0 leg/X . PFX B Y 1 PFX B 0 legesleg/X . SFX C Y 3 SFX C 0 obb . +COMPARATIVE SFX C 0 obb/AX . +SUPERLATIVE SFX C 0 obb/BX . +SUPERSUPERLATIVE Dictionary: 1 nagy/C [MN] Analysis: > nagy nagy[MN] > nagyobb nagy[MN]+COMPARATIVE > legnagyobb nagy[MN]+SUPERLATIVE > legeslegnagyobb nagy[MN]+SUPERSUPERLATIVE
Allowing free compounding yields decrease in precision of recognition, not to mention stemming and morphological analysis. Although lexical switches are introduced to license compounding of bases by Ispell, this proves not to be restrictive enough. For example: # affix file COMPOUNDFLAG X 2 foo/X bar/X With this resource, foobar and barfoo also are accepted words. This has been improved upon with the introduction of direction-sensi- tive compounding, i.e., lexical features can specify separately whether a base can occur as leftmost or rightmost constituent in compounds. This, however, is still insufficient to handle the intricate patterns of compounding, not to mention idiosyncratic (and language specific) norms of hyphenation. The Hunspell algorithm currently allows any affixed form of words, which are lexically marked as potential members of compounds. Hunspell improved this, and its recursive compound checking rules makes it pos- sible to implement the intricate spelling conventions of Hungarian com- pounds. For example, using COMPOUNDWORDMAX, COMPOUNDSYLLABLE, COMPOUND- ROOT, SYLLABLENUM options can be set the noteworthy Hungarian `6-3' rule. Further example in Hungarian, derivate suffixes often modify compounding properties. Hunspell allows the compounding flags on the affixes, and there are two special flags (COMPOUNDPERMITFLAG and (COM- POUNDFORBIDFLAG) to permit or prohibit compounding of the derivations. Suffixes with this flag forbid compounding of the affixed word. We also need several Hunspell features for handling German compounding: # German compounding # set language to handle special casing of German sharp s LANG de_DE # compound flags COMPOUNDBEGIN U COMPOUNDMIDDLE V COMPOUNDEND W # Prefixes are allowed at the beginning of compounds, # suffixes are allowed at the end of compounds by default: # (prefix)?(root)+(affix)? # Affixes with COMPOUNDPERMITFLAG may be inside of compounds. COMPOUNDPERMITFLAG P # for German fogemorphemes (Fuge-element) # Hint: ONLYINCOMPOUND is not required everywhere, but the # checking will be a little faster with it. ONLYINCOMPOUND X # forbid uppercase characters at compound word bounds CHECKCOMPOUNDCASE # for handling Fuge-elements with dashes (Arbeits-) # dash will be a special word COMPOUNDMIN 1 WORDCHARS - # compound settings and fogemorpheme for `Arbeit' SFX A Y 3 SFX A 0 s/UPX . SFX A 0 s/VPDX . SFX A 0 0/WXD . SFX B Y 2 SFX B 0 0/UPX . SFX B 0 0/VWXDP . # a suffix for `Computer' SFX C Y 1 SFX C 0 n/WD . # for forbid exceptions (*Arbeitsnehmer) FORBIDDENWORD Z # dash prefix for compounds with dash (Arbeits-Computer) PFX - Y 1 PFX - 0 -/P . # decapitalizing prefix # circumfix for positioning in compounds PFX D Y 29 PFX D A a/PX A PFX D A Ax/PX A . . PFX D Y y/PX Y PFX D Z z/PX Z Example dictionary: 4 Arbeit/A- Computer/BC- -/W Arbeitsnehmer/Z Accepted compound compound words with the previous resource: Computer Computern Arbeit Arbeits- Computerarbeit Computerarbeits- Arbeitscomputer Arbeitscomputern Computerarbeitscomputer Computerarbeitscomputern Arbeitscomputerarbeit Computerarbeits-Computer Computerarbeits-Computern Not accepted compoundings: computer arbeit Arbeits arbeits ComputerArbeit ComputerArbeits Arbeitcomputer ArbeitsComputer Computerarbeitcomputer ComputerArbeitcomputer ComputerArbeitscomputer Arbeitscomputerarbeits Computerarbeits-computer Arbeitsnehmer This solution is still not ideal, however, and will be replaced by a pattern-based compound-checking algorithm which is closely integrated with input buffer tokenization. Patterns describing compounds come as a separate input resource that can refer to high-level properties of con- stituent parts (e.g. the number of syllables, affix flags, and contain- ment of hyphens). The patterns are matched against potential segmenta- tions of compounds to assess wellformedness.
Unicode character encoding
Both Ispell and Myspell use 8-bit ASCII character encoding, which is a major deficiency when it comes to scalability. Although a language like Hungarian has a standard ASCII character set (ISO 8859-2), it fails to allow a full implementation of Hungarian orthographic conven- tions. For instance, the '--' symbol (n-dash) is missing from this character set contrary to the fact that it is not only the official symbol to delimit parenthetic clauses in the language, but it can be in compound words as a special 'big' hyphen. MySpell has got some 8-bit encoding tables, but there are languages without standard 8-bit encoding, too. For example, a lot of African languages have non-latin or extended latin characters. Similarly, using the original spelling of certain foreign names like ~<i>Angstr~<i>A9|m or Moli~<i>A"re is encouraged by the Hungarian spelling norm, and, since characters 'A' and 'A"' are not part of ISO 8859-2, when they combine with inflections containing characters only in ISO 8859-2 (like elative -bo<i>Al, allative -to<i>Al or delative -ro<i>Al with double acute), these result in words (like ~<i>Angstr~<i>A9|mro<i>Al or Moli~<i>A"re-to<i>Al.) that can not be encoded using any single ASCII encoding scheme. The problems raised in relation to 8-bit ASCII encoding have long been recognized by proponents of Unicode. It is clear that trading effi- ciency for encoding-independence has its advantages when it comes a truly multi-lingual application. There is implemented a memory and time efficient Unicode handling in Hunspell. In non-UTF-8 character encod- ings Hunspell works with the original 8-bit strings. In UTF-8 encoding, affixes and words are stored in UTF-8, during the analysis are handled in mostly UTF-8, under condition checking and suggestion are converted to UTF-16. Unicode text analysis and spell checking have a minimal (0-20%) time overhead and minimal or reasonable memory overhead depends from the language (its UTF-8 encoding and affixation).
Conversion of aspell dictionaries
Aspell dictionaries can be easily converted into hunspell. Conversion steps: dictionary (xx.cwl -> xx.wl): preunzip xx.cwl wc -l < xx.wl > xx.dic cat xx.wl >> xx.dic affix file If the affix file exists, copy it: cp xx_affix.dat xx.aff If not, create it with the suitable character encoding (see xx.dat) echo "SET ISO8859-x" > xx.aff or echo "SET UTF-8" > xx.aff It's useful to add a TRY option with the characters of the dictionary with frequency order to set edit distance suggestions: echo "TRY qwertzuiopasdfghjklyxcvbnmQWERTZUIOPASDFGHJKLYXCVBNM" >>xx.aff
hunspell(1), ispell(1), ispell(4) 2011-02-16 hunspell(4)
hunspell 1.3.2 - Generated Fri Nov 11 06:28:22 CST 2011