Grammalecte  Diff

# Writing rules for Grammalecte
# Writing rules for Grammalecte #

Note: This documentation is a __draft__. Information may be obsolete or incomplete.


## Files required
## FILES REQUIRED ##

The rules file for your language must be named `rules.grx` in the folder `gc_lang/<lang>/`.
The settings file must be named `config.ini`.

These files are simple UTF-8 text files.


## Principles
## PRINCIPLES ##

Grammalecte is a bi-passes grammar checker engine. On the first pass, the
engine checks the text paragraph by paragraph. On the second pass, the engine
check the text sentence by sentence.

You may alter how sentences are split by removing punctuation marks during the first pass.

* flags “LCR” for the regex word boundaries and case sensitiveness
* [optional] option name (the rule is active only if the option defined by user or config is active)
* [optional] rule name (named rules can be disabled by user or by config)
* [optional] priority number
* a regex pattern trigger
* a list of actions

A token rules is defined by:
A token rule is defined by:

* rule name
* [optional] priority number
* one or several lists of tokens
* a list of actions (the action is active only if the option defined by user or config is active)

Token rules must be defined within a graph.

Each graph is defined within the second pass with the command:

        @@@@GRAPH: graph_name|graph_code
    @@@@GRAPH: graph_name|graph_code

A graph ends when another graph is defined or when is found the command:

        @@@@END_GRAPH
    @@@@END_GRAPH

There is no limit to the number of actions and the type of actions a rule can
launch. Each action has its own condition to be triggered.

There are several kinds of actions:

* Error warning, with a message, and optionally suggestions, and optionally an URL
* Error warning, with a message, and optionally suggestions, and optionally a URL
* Text transformation, modifying internally the checked text
* [second pass only] Disambiguation action
* Disambiguation action
* [second pass only] Tagging token
* [second pass only] Immunity rules


On the first pass, you can only write regex rules.
On the second pass, you can write regex rules and token rules. All tokens rules must be written within a graph.

## Syntax details


## REGEX RULE SYNTAX ##

### Comments

Lines beginning with `#` are comments.


### End of parsing

With the command `#END` at the beginning of a line, the parser won’t go further.
Whatever is written after will be considered as comments.


## Regex rule syntax

    __LCR/option(rulename)!priority__
        pattern
            <<- condition ->> error_suggestions             # message_error|URL
            <<- condition ~>> text_rewriting
            <<- condition =>> commands_for_disambiguation
            ...

Patterns are written with the Python syntax for regular expressions:
http://docs.python.org/library/re.html

There can be one or several actions for each rule, executed following the order they are
written.

Optional:
Optional: option, rulename, priority, condition, URL

* option
* rulename
* priority
* conditions
* URL


LCR flags means:

* L: Left boundary for the regex
* C: Case sensitiveness
* R: Right boundary for the regex

    __[i]__
    __<s]__
    __[u>__
    __<s>__


User option activating/disactivating is possible with an option name placed
User option activating/deactivating is possible with an option name placed
just after the LCR flags, i.e.:

    __[i]/option1__
    __[u]/option2__
    __[s>/option1__
    __<u>/option3__
    __<i>/option3__

    __<i]__  \b([?!.])([A-Z]+) <<- ->> \1 \2     # Missing space?

Example. Back reference in messages.

    (fooo) bar <<- ->> foo      # “\1” should be:


### Group positioning codes for JavaScript:

There is no way in JavaScript to know where a captured group starts and ends. To avoid misplacement, regex rules may specify group positioning codes which indicate to the grammar checker where is the position of the captured groups.

A group positioning code always begins by `@@`. If there is several codes, they are separated by a comma `,`.

Other codes:

    0 1 2 3 ... n       left boundary position from left
    -1 -2 -2 ... -n     right boundary position from right
    $                   extreme right boundary
    w                   somewhere with word boundaries
    *                   something somewhere
    **                  something somewhere after previous group

Examples:

    ([A-ZÉÈÂÎ][\w-]+) [A-ZÉÈÂ]([.]) ([A-ZÉÈÂ][\w-]+)  @@0,*,$
    " ([?!;])"  @@1


### Pattern matching

Repeating pattern matching of a single rule continues after the previous matching, so
Repeating pattern matching of a single rule continues after the previous matching, so instead of general multiword patterns, like
instead of general multiword patterns, like

        (\w+) (\w+) <<- some_check(\1, \2) ->> \1, \2 # foo

use

        (\w+) <<- some_check(\1, word(1)) ->> \1, # foo


## TOKEN RULES ##
### Definitions

Token rules must be defined within a graph.

### Token rules syntax
Grammalecte supports definitions to simplify the description of complex rules.

    __rulename!priority__
        list_of_tokens
        list_of_tokens
        list_of_tokens
        ...
            <<- /option/ condition ->> suggestions|URL
            <<- /option/ condition ~>> rewriting
            <<- /option/ condition =>> disambiguation
            <<- /option/ condition />> tagging
            <<- /option/ condition !>> <immunity>
            ...
             
        list_of_tokens
        ...
            <<- action1
            <<- action2
            ...

With token rules, for one rule name, you can define several blocks of list of tokens with different kinds of actions. Each block must be separated by an empty line.

Optional: priority, option, condition, URL

### Tokens

Tokens can be defined in several ways:

* Value (the text of the token). Examples: `word`, `<start>`, `<end>`, `,`.
* Lemma: `>lemma`.
* Regex: `~pattern`, `~pattern¬antipattern`.
* Regex on morphologies: `@pattern`, `@pattern¬antipattern`.
* Tags: `/tag`.
* Metatags: *NAME. Examples: `*WORD`, `*NUM`, `*SIGN`, etc.
* Jump over token: `<>`

Selection of tokens: `[value1|value2||>lemma|~pattern|@pattern|*META|/tag|…]`

Conditional token: `?token¿`

Conditional selection of token: `?[token1|token2|…]¿`

### Token references

Positive references are defined by a positive integer (> 0). Examples: `\1`, `\2`, `\3`, etc.
If there is at least one token set between parenthesis, these numbers refer to tokens between parenthesis, ignoring all others.
If there is no token between parenthesis, these numbers refer to tokens found in order defined by the rule triggered.

Negative references are defined by a negative integer (< 0). Examples: `\-1`, `\-2`, `\-3`, etc.
These numbers refer to the tokens beginning by the last one found by the rule triggered.

Examples:

    tokens:             alpha       beta        gamma       delta       epsilon
    positive refs:      1           2           3           4           5
    negative refs:      -5          -4          -3          -2          -1

    tokens:             alpha       (beta)      gamma       (delta)     epsilon
    positive refs:                  1                       2
    negative refs:      -5          -4          -3          -2          -1

    tokens:             alpha       (beta)      ?gamma¿     (delta)     epsilon
    positive refs:                  1                       2
    negative refs:      (-5/-4)     (-4/-3)     (-3/none)   -2          -1


## CONDITIONS ##

Conditions are Python expressions, they must return a value, which will be
evaluated as boolean. You can use the usual Python syntax and libraries.

With regex rules, you can call pattern subgroups via `\1`, `\2`… `\0` is the full pattern.

Example:

    these (\w+)
        <<- \1 == "man" -1>> men        # Man is a singular noun.

You can also apply functions to subgroups like: `\1.startswith("a")` or `\3.islower()` or `re.search("pattern", \2)`.

With token rules, you can also call each token with their reference, like `\1`, `\2`... or `\-1`, `\-2`...

Example:

    foo [really|often|sometimes] bar
        <<- ->> \1 \-1                  # We say “foo bar”.
    DEF: name pattern


### Functions for regex rules
Usage in the rules:

`word(n)`

>   Catches the nth next word after the pattern (separated only by white spaces).
>   Returns None if no word caught
    ({name}) (\w+) ->> "\1-\2"          # Missing hyphen?

`word(-n)`

>   Catches the nth next word before the pattern (separated only by white spaces).
>   Returns None if no word caught

`textarea(regex[, neg_regex])`
### Multiple suggestions

>    Checks if the full text of the checked area (paragraph or sentence) matches the regex.

`morph(n, regex[, neg_regex][, no_word=False])`
Use `|` in the replacement text to add multiple suggestions:

>   Checks if all tags of the word in group n match the regex.
>   If neg_regex = "*", returns True only if all morphologies match the regex.
>   If there is no word at position n, returns the value of no_word.

`analyse(n, regex[, neg_regex][, no_word=False])`
Example. Foo, FOO, Bar and BAR suggestions for the input word "foo".

>   Checks if all tags of the word in group n match the regex.
>   If neg_regex = "*", returns True only if all morphologies match the regex.
>   If there is no word at position n, returns the value of no_word.

### Functions for token rules

`value(n, values_string)`

>   Analyses the value of the nth token.
>   The <values_string> contains values separated by the sign `|`.
>   Example: `"|foo|bar|"`

`morph(n, "regex"[, "neg_regex"][, trim_left=0][, trim_right=0])`
`analyse(n, "regex"[, "neg_regex"][, trim_left=0][, trim_right=0])`

>   Same action with `morph()` and `morph0()` for regex rules.
>   Parameters <trim_left> and <trim_right> removed n characters at left or the right of the token before performing an analyse.

`space_after(n, min_space[, max_space])`

>   Returns True if the next token after token n is separated with at least <min_space> blank spaces and at most with <max_space> blank spaces.

`tag(n, tag)`

>   Returns True if <tag> exists on taken the nth token.

`tag_before(n, tag)`

>   Returns True if <tag> is found any token before the nth tag.
    foo <<- ->> Foo|FOO|Bar|BAR         # Did you mean:
   
`tag_after(n, tag)`

>   Returns True if <tag> is found any token after the nth tag.

### Functions for regex and token rules
### No suggestion

`__also__`

>   Returns True if the previous condition returned True.
>   Example: `<<- __also__ and condition2 ->>`
You can display message without making suggestions. For this purpose,
use a single character _ in the suggestion field.

`__else__`

>   Returns False if the previous condition returned False.
>   Example: `<<- __else__ and condition2 ->>`

`option(option_name)`
Example. No suggestion.

>   Returns True if <option_name> is activated else False

Note: the analysis is done on the preprocessed text.
    foobar <<- ->> _                    # Message

`after(regex[, neg_regex])`

>   Checks if the text after the pattern matches the regex.

`before(regex[, neg_regex])`

>   Checks if the text before the pattern matches the regex.

### Default variables

`sCountry`

>   Contains the current country locale of the checked paragraph.

    colour <<- sCountry == "US" ->> color   # Use American English spelling.


## ACTIONS ##

There are 5 kinds of actions:

1. Suggestions. The grammar checker suggests corrections.
2. Text processor. A internal process to modify the text internally. This is used to simplify grammar checking.
     * text rewriting
     * text deletion
     * token rewriting
     * token merging
     * token deletion
3. Disambiguation. Select, exclude or define morphologies of tokens.
4. Tagging. Add information on token.
5. Immunity. Prevent suggestions to be triggered.


### Positioning

Positioning is valid only for error creation and text rewriting.
Positioning is valid for suggestions, text processing, tagging and immunity.

By default, the full pattern will be underlined with blue. You can shorten the
underlined text area by specifying a back reference group of the pattern.
Instead of writing ->>, write -n>>  n being the number of a back reference
group. Actually,  ->>  is similar to  -0>>
By default, rules apply on the full text triggered. You can shorten the
effect of rules by specifying a back reference group of the pattern or token references.

Instead of writing `->>`, write `-n>>`  n being the number of a back reference
group. Actually,  `->>`  is similar to  `-0>>`.

Example:

    (ying) and yang <<- -1>> yin # Did you mean:

    __[s]__ (Mr.) [A-Z]\w+ <<- ~1>> Mr

With the rule B, only the first group is underlined:

    ying and yang
    ^^^^


### Errors and suggestions

The command to suggest something is: `->>`.

#### Multiple suggestions

Use `|` in the replacement text to add multiple suggestions:

Example. Foo, FOO, Bar and BAR suggestions for the input word "foo".

    foo <<- ->> Foo|FOO|Bar|BAR         # Did you mean:

#### No suggestion

You can display message without making suggestions. For this purpose,
use a single character _ in the suggestion field.

Example. No suggestion.

    foobar <<- ->> _                    # Message

### Longer explanations with URLs
#### Longer explanations with URLs

Warning messages can contain optional URL for longer explanations.

    your’s
        <<- ->> yours
            # Possessive pronoun:|http://en.wikipedia.org/wiki/Possessive_pronoun

#### Expressions in suggestion or replacement

Suggestions started by an equal sign are Python string expressions extended with possible back references and named definitions:

Example:

    <<- ->> ='"' + \1.upper() + '"'      # With uppercase letters and quotation marks
    <<- ~>> =\1.upper()


### Text rewriting

**WARNING**: The replacing text must be shorter than the replaced text or have the same length. Breaking this rule will misplace following error reports.
You have to ensure yourself the rules comply with this constraint, the text processor won’t do it for you.

The command for text rewriting is: `~>>`.

Example. Replacing a string by another.

    Mr. [A-Z]\w+ <<- ~>> Mister

**WARNING**: The replacing text must be shorter than the replaced text or have the
same length. Breaking this rule will misplace following error reports. You
have to ensure yourself the rules comply with this constraint, Grammalecte
won’t do it for you.

Specific commands for text rewriting:

`~>> *`

>   Replace by whitespaces

`~>> @`

>   Replace with arrobas, useful mostly at first pass, where it is advised to
>   Replace with the at sign, useful mostly at first pass, where it is advised to check usage of punctuations and whitespaces.
>   check usage of punctuations and whitespaces.
>   Successions of @ are automatically removed at the beginning of the second pass.

`~>> _`

>   Replace with underscores. Just a filler.
>   These characters won’t be removed at the beginning of the second pass.

You can use positioning with text rewriting actions.

    Mr(. [A-Z]\w+) <<- ~1>> *

You can also call Python expressions.

    __[s]__ Mr. ([a-z]\w+) <<- ~1>> =\1.upper()


### Text processing

The text processor is useful to simplify texts and write simplier checking
The text processor is useful to simplify texts and write simpler checking
rules.

For example, sentences with the same grammar mistake:

    These “cats” are blacks.
    These cats are “blacks”.
    These cats are absolutely blacks.
    These stupid “cats” are all blacks.
    These unknown cats are as per usual blacks.

Instead of writting complex rules or several rules to find mistakes for all possible
cases, you can use the text preprocessor to simplify the text.
Instead of writing complex rules or several rules to find mistakes for all possible cases, you can use the text preprocessor to simplify the text.

To remove the chars “”, write:

    [“”] ~>> *

The * means: replace text by whitespaces.

    Mister <<- ~>> Mr
    (Mrs?)[.] <<- ~>> \1


### Disambiguation

When Grammalecte analyses a word with morph, before requesting the
POS tags to the dictionary, it checks if there is a stored marker for the
When the grammar checker analyses a token with `morph()`, before requesting the POS tags to the dictionary, it checks if there is a stored marker for the position of the token. If a marker is found, it uses the stored data and don’t make request to the dictionary.
position where the word is. If there is a marker, Grammalecte uses the stored
data and don’t make request to the dictionary.

The disambiguation commands store POS tags at the position of a word.
The command for disambiguation is: `=>>`. No positioning allowed.

There is 3 commands for disambiguation.
There are 4 commands for disambiguation.

`select(n, pattern)`

>   stores at position n only the POS tags of the word matching the pattern.
>   At reference n, select morphologies that match the pattern.

`exclude(n, pattern)`

>   At reference n, exclude morphologies that match the pattern.
>   stores at position n the POS tags of the word, except those matching the
    pattern.

`define(n, [morph_list])`

>   At reference n, set the listed morphologies (a list of strings).

`define(n, [definitions])`
`add_morph(n, [morph_list])`

>   stores at position n the POS tags in definitions (a list of strings).
>   At reference n, add the listed morphologies (a list of strings).

Examples:

    =>> select(\1, "po:noun is:pl")
    =>> exclude(\1, "po:verb")
    =>> define(\1, ["po:adv"])
    =>> exclude(\1, "po:verb") and define(\2, ["po:adv"]) and select(\3, "po:adv")

Note: select(), exclude() and define() ALWAYS return True.
Note: All these functions ALWAYS return True.

If select() and exclude() generate an empty list, no marker is set.
If `select()` and `exclude()` generate an empty list, nothing change.

With define, you must set a list of POS tags. Example:
With `define()` and `add_morph()`, you must set a list of POS tags. Example:

    define(\1, ["po:nom is:plur", "po:adj is:sing", "po:adv"])

    =>> define(\1, ["po:nom is:plur", "po:adj is:sing", "po:adv"])
    =>> add_morph(\1, ["po:adv"])

### Conditions
### Tagging

Conditions are Python expressions, they must return a value, which will be
evaluated as boolean. You can use the usual Python syntax and libraries.

**Only for token rules**. Tagging can be done with the command `/>>`. You can set one or several tags at once. Use `|` as a separator.
You can call pattern subgroups via \0, \1, \2…

Example:

    these (\w+)
        <<- \1 == "man" -1>> men        # Man is a singular noun. Use the plural form:

You can also apply functions to subgroups like:

    \1.startswith("a")
    \3.islower()
    re.search("pattern", \2)


### Standard functions

`word(n)`

>   catches the nth next word after the pattern (separated only by white spaces).
>   returns None if no word catched

`word(-n)`

Example: `/>> a_tag` to set the same tag on all takens of the rule.
>   catches the nth next word before the pattern (separated only by white spaces).
>   returns None if no word catched

Example: `/3>> a_tag` to set the tag on the third token.
`after(regex[, neg_regex])`

Example: `/>> a_tag|another_tag` to set two tags.
>   checks if the text after the pattern matches the regex.

`before(regex[, neg_regex])`

You can know if a token is tagged with eh function `tag()` and you can know if tags have been set on previous or following tokens with `tag_before()` and `tag_after()`.
>   checks if the text before the pattern matches the regex.

`textarea(regex[, neg_regex])`

### Immunity
>    checks if the full text of the checked area (paragraph or sentence) matches the regex.

`morph(n, regex[, neg_regex][, no_word=False])`

**Only for token rules**. A immunity rule set a flag on token(s) who are not supposed to be considered as an error. If any other rules find an error, it will be ignored. If an error has already been found, it will be removed.
>   checks if all tags of the word in group n match the regex.
>   if neg_regex = "*", returns True only if all morphologies match the regex.
>   if there is no word at position n, returns the value of no_word.

`morph0(n, regex[, neg_regex][, no_word=False])`

Example: `!2>>` means no error can be set on the second token.
>   checks if all tags of the word in group n match the regex.
>   if neg_regex = "*", returns True only if all morphologies match the regex.
>   if there is no word at position n, returns the value of no_word.

Example: `!>>` means all tokens will be considered as correct.

`option(option_name)`
The immunity rules are useful to create simple antipattern that will simplify writing of other rules.

>   returns True if option_name is activated else False

Note: the analysis is done on the preprocessed text.

## OTHER COMMANDS ##

### Default variables

### Comments
`sCountry`

>   It contains the current country locale of the checked paragraph.

Lines beginning with `#` are comments.
    colour <<- sCountry == "US" ->> color       # Use American English spelling.


### End of parsing

### Expressions in suggestion or replacement

With the command `#END` at the beginning of a line, the parser won’t go further.
Suggestions started by an equal sign are Python string expressions
extended with possible back references and named definitions:

Whatever is written after will be considered as comments.
Example:

    <<- ->> ='"' + \1.upper() + '"'         # With uppercase letters and quotation marks
    <<- ~>> =\1.upper()

### Definitions

## Token rules

Grammalecte supports definitions to simplify the description of complex rules.
Token rules must be defined within a graph.


### Tokens

Tokens can be defined in several ways:

* Value (meaning the text of the token). Examples: `word`, `<start>`, `<end>`, `,`.
* Lemma: `>lemma`.
* Regex: `~pattern`, `~pattern¬antipattern`.
* Regex on morphologies: `@pattern`, `@pattern¬antipattern`.
* Tags: `/tag`.
* Metatags: *NAME. Examples: `*WORD`, `*NUM`, `*SIGN`, etc.

Selection of tokens: `[token1|token2|>lemma1|>lemma2|~pattern1|@pattern1|…]`

Definition:
Conditional token: `?token¿`

Conditional selection of token: `?[token1|token2|…]¿`

    DEF: name definition

### Token references

Usage: `{name}` will be replaced by its definition
Positive references are defined by a positive integer `>= 1`. Examples: \1, \2, \3, etc.
If there is at least one token set between parenthesis, these numbers refer to tokens between parenthesis, ignoring all others.
If there is no token between parenthesis, these numbers refer to tokens found in order defined by the rule triggered.

Negative references are defined by a negative integer `<= -1`. Examples: \-1, \-2, \-3, etc.
These numbers refer to the tokens beginning by the last one found by the rule triggered.

Examples:
Example:

    tokens:             alpha       beta        gamma       delta       epsilon
    positive refs:      1           2           3           4           5
    negative refs:      -5          -4          -3          -2          -1

    DEF: word_3_letters     \w\w\w+  
    tokens:             alpha       (beta)      gamma       (delta)     epsilon
    positive refs:                  1                       2
    negative refs:      -5          -4          -3          -2          -1
    DEF: uppercase_token    ~^[A-Z]+$
    DEF: month_token        [January|February|March|April|May|June|July|August|September|October|November|december]

    tokens:             alpha       (beta)      ?gamma¿     (delta)     epsilon
    positive refs:                  1                       2
    negative refs:      (-4/-5)     (-3/-4)     (-3/none)   -2          -1
    ({word_3_letters}) (\w+) <<- condition ->> suggestion     # message|URL

    {uppercase_token} {month_token}
        <<- condition ->> message                             # message|URL