Grammalecte  Diff

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


## 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

Each rule name must be unique.

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

    __[s](rulename)__
        foo bar
            <<- ->> foo-bar     && Missing hyphen.
            <<- ~>> foo-bar


### Simple-line or multi-line rules

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

Examples:

    __<s>(rulename)__ pattern <<- condition ->> replacement  && message

    __<s>(rulename)__
        pattern
            <<- condition ->> replacement
            && message
            <<- condition ->> suggestion  && message
            <<- condition ~>> text_rewriting
            <<- =>> disambiguation


### Whitespaces at the border of patterns or suggestions

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

    __<s>(rulename)__  "  +" <<- ->> " "      && Remove extra space(s).

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


### 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.

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

    \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 `,`.

    " ([?!;])"  @@1


### 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


## TOKEN RULES ##

Token rules must be defined within a graph.

### Token rules syntax

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”.


### Functions for regex rules

`word(n)`

>   Catches the nth next word after the pattern (separated only by white spaces).

### Default variables

`sCountry`

>   Contains the current country locale of the checked paragraph.

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

`sContext`

>   The name of the application running (Python, Writer…)


## ACTIONS ##

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


**Comparison**

Rule A:

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

Rule B:

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

With the rule A, the full pattern is underlined:

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

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

#### 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

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.

    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.

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

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

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

Example:

    DEF: word_3_letters     \w\w\w+  
    DEF: uppercase_token    ~^[A-Z]+$
    DEF: month_token        [January|February|March|April|May|June|July|August|September|October|November|december]

    ({word_3_letters}) (\w+) <<- condition ->> suggestion     && message|URL

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