Grammalecte  Check-in [4592c7bfb6]

# Writing rules for Grammalecte
WRITING RULES FOR GRAMMALECTE

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

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

## 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.

The command to switch to the second pass is `[++]`.

In each pass, you can write as many rules as you need.

There are two kinds of rules:

* regex rules (triggered by a regular expression)
* token rules (triggered by a succession of tokens)

A regex rule is defined by:

* [optional] flags “LCR” for the regex word boundaries and case sensitiveness
* flags “LCR” for the regex word boundaries and case sensitiveness
* a regex pattern trigger
* a list of actions
* [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:

* rule name
* [optional] priority number
* one or several lists of tokens (triggers)
* 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: graph_name|graph_code

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

        @@@@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
* Text transformation, modifying internally the checked text
* Disambiguation action, setting tags on a position
* Tagging
* [second pass only] Disambiguation action
* [second pass only] Tagging token
* [second pass only] Immunity rules


The rules file for your language must be named `rules.grx`.
The settings file must be named `config.ini`.
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
All these files are simple utf-8 text file.

UTF-8 is mandatory.


# Comments #
### Comments

Lines beginning with `#` are comments.


# End of file #
### End of parsing

With the command:

        #END

at the beginning of a line, the parser won’t go further.
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 #
## Regex rule syntax

        __LCR/option(rulename)__
            pattern
            <<- condition ->> error_suggestions  # message_error|http://awebsite.net...
    __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 the order they are
There can be one or several actions for each rule, executed following the order they are
written.

Conditions are optional, i.e.:
Optional:

* option
        <<- ~>> replacement
* rulename
* priority
* conditions
* URL


LCR flags means:

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

>   `u`     uppercase allowed for lowercase characters

>>          i.e.:  "Word"  becomes  "W[oO][rR][dD]"

Examples:

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


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

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

Rules can be named:

        __[i]/option1(name1)__  pattern
        __[u]/option2(name2)__  pattern
        __[s>/option1(name3)__  pattern
        __<u>(name4)__          pattern
        __<i>(name5)__          pattern
    __[i]/option1(name1)__
    __[u]/option2(name2)__
    __[s>/option1(name3)__
    __<u>(name4)__
    __<i>(name5)__

Each rule name must be unique.


The LCR flags are also optional. If you don’t set these flags, the default LCR
flags will be:

        __[i]__
    __[i]__

Example. Report “foo” in the text and suggest "bar":
Example. Report “foo” in the text and suggest “bar”:

        foo <<- ->> bar # Use bar instead of foo.
    foo <<- ->> bar         # Use bar instead of foo.

Example. Recognize and suggest missing hyphen and rewrite internally the text
with the hyphen:

        __[s]__ foo bar
            <<- ->> foo-bar # Missing hyphen.
    __[s]__
        foo bar
            <<- ->> foo-bar     # Missing hyphen.
            <<- ~>> foo-bar


## Simple-line or multi-line rules ##
### Simple-line or multi-line rules

Rules can be break to multiple lines by leading tabulators or spaces.
Rules can be break to multiple lines by leading spaces.
You should use 4 spaces.

Examples:

    __<s>__ pattern <<- condition ->> replacement # message

        __<s>__ pattern
    __<s>__
        pattern
            <<- condition ->> replacement
            # message
            <<- condition ->> suggestion # message
            <<- condition ~>> text_rewriting
            <<- =>> disambiguation

        __<s>__ pattern <<- condition ->> replacement # message


## Whitespaces at the border of patterns or suggestions ##
### Whitespaces at the border of patterns or suggestions

Example: Recognize double or more spaces and suggests a single space:

        __<s>__  "  +" <<- ->> " "      # Extra space(s).
    __<s>__  "  +" <<- ->> " "      # Remove extra space(s).

Characters `"` protect spaces in the pattern and in the replacement text.


## Pattern groups and back references ##
### Pattern groups and back references

It is usually useful to retrieve parts of the matched pattern. We simply use
parenthesis in pattern to get groups with back references.

Example. Suggest a word with correct quotation marks:

        \"(\w+)\" <<- ->> “\1”      # Correct quotation marks.
    \"(\w+)\" <<- ->> “\1”      # Correct quotation marks.

Example. Suggest the missing space after the !, ? or . signs:
Example. Suggest the missing space after the signs `!`, `?` or `.`:

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

Example. Back reference in messages.

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


## Pattern matching ##
### Pattern matching

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

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

use

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


## Name definitions ##
### Definitions

Grammalecte supports name definitions to simplify the description of the
Grammalecte supports definitions to simplify the description of complex rules.
complex rules.

Example:

        DEF: name pattern
    DEF: name pattern

Usage in the rules:

        ({name}) (\w+) ->> "\1-\2" # Missing hyphen?
    ({name}) (\w+) ->> "\1-\2"          # Missing hyphen?


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


## No suggestion ##
### 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
    foobar <<- ->> _                    # Message


## Positioning ##
### Positioning

Positioning is valid only for error creation and text rewriting.

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>>

Example:

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

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


### Comparison ###
**Comparison**

Rule A:

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

Rule B:

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

With the rule A, the full pattern is underlined:

        ying and yang
        ^^^^^^^^^^^^^
    ying and yang
    ^^^^^^^^^^^^^

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

        ying and yang
        ^^^^
    ying and yang
    ^^^^


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

Warning messages can contain optional URL for longer explanations.

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



# Text rewriting #
### Text rewriting

Example. Replacing a string by another.

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

WARNING: The replacing text must be shorter than the replaced text or have the
**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 by whitespaces

`~>> @`

>   replace by arrobas, useful mostly at first pass, where it is advised to
>   Replace with arrobas, useful mostly at first pass, where it is advised to
>   check usage of punctuations and whitespaces.
>   @ are automatically removed at the beginning of the second pass.
>   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>> *
    Mr(. [A-Z]\w+) <<- ~1>> *

You can also call Python expressions.

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


# Text preprocessing and multi-passes checking #

### Text processing
On each pass, Lightproof uses rules written in the text preprocessor to modify
internally the text before checking the text.

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

For example, sentences with the same grammar mistake:

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

To remove the chars “”, write:

        [“”] ->> *
    [“”] ~>> *

The * means: replace text by whitespaces.

Similarly to grammar rules, you can add conditions:

        \w+ly <<- morph(\0, "adverb") ->> *
    \w+ly <<- morph(\0, "adverb") ~>> *

You can also remove a group reference:

        these (\w+) (\w+) <<- morph(\1, "adjective") and morph(\2, "noun") -1>> *
        (am|are|is|were|was) (all) <<- -2>> *
    these (\w+) (\w+) <<- morph(\1, "adjective") and morph(\2, "noun") ~1>> *
    (am|are|is|were|was) (all) <<- ~2>> *
    as per usual <<- ~>> *

With these rules, you get the following sentences:

        These  cats  are black.
        These cats are  black .
        These cats are            black.
        These         cats  are     black.
        These         cats are              black.
    These  cats  are blacks.
    These cats are  blacks .
    These cats are            blacks.
    These         cats  are     blacks.
    These         cats are              blacks.

These grammar mistakes can be detected with one simple rule:

        these +(\w+) +are +(\w+s)
            <<- morph(\1, "noun") and morph(\2, "plural")
            -2>> _              # Adjectives are invariable.
    these +(\w+) +are +(\w+s)
        <<- morph(\1, "noun") and morph(\2, "plural")
        -2>> _              # Adjectives are invariable.

Instead of replacing text with whitespaces, you can replace text with @.

        https?://\S+ ->> @
    https?://\S+ <<- ~>> @

This is useful if at first pass you write rules to check successive whitespaces.
@ are automatically removed at the second pass.

You can also replace any text as you wish.

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


# Disambiguation #
### 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
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.

`define(n, [definitions])`

>   stores at position n the POS tags in definitions (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")
    =>> 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: select(), exclude() and define() ALWAYS return True.

If select and exclude generate an empty list, no marker is set.
If select() and exclude() generate an empty list, no marker is set.

With define, 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"])


# Conditions #
### 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.

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


## Standard functions ##
### 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)`

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

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

>   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.


`option(option_name)`

>   returns True if option_name is activated else False

Note: the analysis is done on the preprocessed text.


# Default variables #
### Default variables

`sCountry`

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

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



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


# Token rules
## Token rules

Token rules must be defined within a graph.


## Tokens
### 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|…]`

Conditional token: `?token¿`

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


## Token references
### Token references

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:

        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           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          -3          -2          -1

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