gencpp/docs/Parsing.md

50 lines
2.4 KiB
Markdown
Raw Normal View History

# Parsing
The library features a naive parser tailored for only what the library needs to construct the supported syntax of C++ into its AST.
This parser does not, and should not do the compiler's job. By only supporting this minimal set of features, the parser is kept under 5000 loc.
Everything is done in one pass for both the preprocessor directives and the rest of the language.
The parser performs no macro expansion as the scope of gencpp feature-set is to only support the preprocessor for the goal of having rudimentary awareness of preprocessor ***conditionals***, ***defines***, and ***includes***.
*(Conditionals and defines are a TODO)*
The keywords supported for the preprocessor are:
* include
* define
* if
* ifdef
* elif
* endif
* undef
Just like with actual preprocessor, each directive # line is considered one preproecessor unit, and will be treated as one Preprocessor AST. *These ASTs will be considered members or entries of braced scope they reside within*.
All keywords except *include* are suppported as members of a scope for a class/struct, global, or namespace body.
Any preprocessor definition abuse that changes the syntax of the core language is unsupported and will fail to parse if not kept within an execution scope (function body, or expression assignment).
The parsing implementation supports the following for the user:
```cpp
CodeClass parse_class ( StrC class_def );
CodeEnum parse_enum ( StrC enum_def );
CodeBody parse_export_body ( StrC export_def );
CodeExtern parse_extern_link ( StrC exten_link_def);
CodeFriend parse_friend ( StrC friend_def );
CodeFn parse_function ( StrC fn_def );
CodeBody parse_global_body ( StrC body_def );
CodeNamespace parse_namespace ( StrC namespace_def );
CodeOperator parse_operator ( StrC operator_def );
CodeOpCast parse_operator_cast( StrC operator_def );
CodeStruct parse_struct ( StrC struct_def );
CodeTemplate parse_template ( StrC template_def );
CodeType parse_type ( StrC type_def );
CodeTypedef parse_typedef ( StrC typedef_def );
CodeUnion parse_union ( StrC union_def );
CodeUsing parse_using ( StrC using_def );
CodeVar parse_variable ( StrC var_def );
```
***Parsing will aggregate any tokens within a function body or expression statement to an untyped Code AST.***