Since we have implemented the functions to add and exlcude phrases, the
commit allows users to use a table to change the output of a phrase
without changing its BPMF reading and score, when the "phrase replacement"
mode is on.
It could help users to switch a specific input scenario and the ordinary
one. For example, if a user wants to work on financial Chinese numbers
like 壹、貳、參, he or she may want the characters to have higher score
as the normal numbers like 一、二、三. The commit can let the users to
temporarily replace 一、二、三 to 壹、貳、參 by just turn on "phrase
replacement" mode and prepare a custom table.
The conversion is not done on the output phase like how we do
Traditional/Simplified Chinese conversion. What the phrase replacement
table does is to slightly modify the language model. The replacement
takes place on walking the nodes and candidates list.
A user can enable the mode and edit the table from the input menu. Since
the function is quite advanced, the menu items are hidden until the user
holds the option key.
The table is a plain text file. Each line contains a "from" and "to".
For example
```
一 壹
```
However, if the user also want all other phrase contain 一 to become 壹,
all of the phrases have to be built into the table
```
一百 壹佰
一千 壹仟
一萬 壹萬
一百萬 壹百萬
```
Since there is no probability information for users' custom phrases,
they should be stored in a format differs from data.txt. Using the same
format and FastLM to parse user phrases just because of laziness but it
is not the right way.
The pull request adds a new language model class to parse user phrases.
It also update the input method controller to adopt the new user phrase
format.
The reference of the global language models were stored in the class
InputMethodController, however, the global models are global but not a
part of the input method controller, and the input method controller
only use one of the models (McBopomofo/Plain Bopomofo). I guess it
somehow violates SRP and there should be a better place for the global
models.
zonble
Lukhnos Liu