Changes in version 3

Changes in public API

Detailed list of changes in the public API

The number of elements of the tuple struct used in the enum variant Trm of the enum parol::grammar::symbol::Terminal has changed.
The number of elements of the tuple struct used in the enum variant N of the enum parol::grammar::symbol::Symbol has changed.
In the module parol::parser::parol_grammar some public enums have similar changes in some variants.

I expect that most applications that use parol v2 can upgrade to v3 without problems. The changes listed above only affect applications that use the parol library for very specific tasks.

New feature "User defined member names"

You can now specify for each symbol on the right-hand side of a production how its corresponding member in the generated struct should be named.

To achieve this you can use the newly introduced @ operator.

Declaration :
    ...
    | "%nt_type" Identifier@nt_name "="^ UserTypeName@nt_type
    ...

In this example the Identifier in the production will be named nt_name and the UserTypeName will receive the name nt_type in the generated struct data type for this production.

New feature "Non-terminal types"

You can now easily define a user type to which each occurrence of a certain non-terminal should be automatically converted to. This is done like in the following example:

%nt_type ScannerState = crate::parser::parol_grammar::ScannerConfig

It is similar to the already available %user_type with what you could define an alias for a user defined type which in turn you could apply to single symbols on the right-hand side of grammar productions. The %nt_type can't be used on terminals but it makes the application to non-terminals much easier. Here is the old version used in parol itself before (only partial)

%user_type ScannerConfig = crate::parser::parol_grammar::ScannerConfig
// ...
%%
// ...
Prolog
: StartDeclaration { Declaration } { ScannerState: ScannerConfig }
;

And here is the new variant in which %nt_type is used.

%nt_type ScannerState = crate::parser::parol_grammar::ScannerConfig
// ...
%%
// ...
Prolog
: StartDeclaration { Declaration } { ScannerState }
;

The non-terminal ScannerState was defined to be automatically converted to ScannerConfig.

It is semantically completely identical to use %user_type for a certain non-terminal and then apply the defined %user_type alias to each occurrence of the concerned non-terminal in the grammar definition explicitly.

New feature "Terminal type"

You can now easily define a user type to which each occurrence of a terminal should be automatically converted to. This is done like in the following example:

%t_type crate::parol_ls_grammar::OwnedToken

There can be only one type defined to which all terminals are converted to.

More precisely, if there are more such directives given the last one will win.

Here is the old version used in parol-ls itself before (only partial)

%user_type OwnedToken = crate::parol_ls_grammar::OwnedToken
// ...
%%
// ...
ScannerSwitch
    : "%sc": OwnedToken '(': OwnedToken [ Identifier ] ')': OwnedToken
    | "%push": OwnedToken '(': OwnedToken Identifier ')': OwnedToken
    | "%pop": OwnedToken '(': OwnedToken ')': OwnedToken
    ;

And here is the new variant in which %t_type is used.

%t_type crate::parol_ls_grammar::OwnedToken
// ...
%%
// ...
ScannerSwitch
    : "%sc" '(' [ Identifier ] ')'
    | "%push" '(' Identifier ')'
    | "%pop" '(' ')'
    ;

All terminals are automatically defined to be converted to crate::parol_ls_grammar::OwnedToken.

parol re-exports parol_runtime

This simplifies the use and avoids version conflicts between both libraries.

The initial Cargo.toml will then simple be similar like this:

[package]
name = "re_export"
version = "0.1.0"
edition = "2021"

[dependencies]
anyhow = "1.0"
env_logger = "0.11"
parol_runtime = "2.2"
thiserror = "2.0"

[build-dependencies]
parol = "3.0.0"

This makes a lot more sense, since you would expect to reference parol_runtime in your parser crate and have parol as build dependency.

Anyway, as before, it is advisable to use parol_runtime in the version that parol in the build dependencies uses. These two crates are precisely coordinated.

To check this you can use the following command: