source: src/AST/porting.md @ 14cebb7a

arm-ehcleanup-dtorsjacob/cs343-translationjenkins-sandboxnew-astnew-ast-unique-expr
Last change on this file since 14cebb7a was 14cebb7a, checked in by Andrew Beach <ajbeach@…>, 3 years ago

Removed trailing white-space in AST.

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1# Porting notes for new AST #
2
3## Pointer Types ##
4* raw pointer `T*` is used for construction, but not storage
5* strong pointer `ast::ptr<T>` is used for an ownership relationship
6* weak pointer `ast::readonly<T>` is used for an observation relationship
7
8## Visitors ##
9* `Visitor` and `Mutator` are combined into a single `ast::Visitor` class
10  * Base nodes now override `Node* accept( Visitor& v ) = 0` with, e.g. `Stmt* accept( Visitor& v ) override = 0`
11* `PassVisitor` is replaced with `ast::Pass`
12
13## Structural Changes ##
14`CodeLocation` has been devolved from `BaseSyntaxNode` to `ast::ParseNode`
15* excludes `ast::Type` from carrying location information
16* `CodeLocation` is a mandatory constructor field for `ast::ParseNode`
17  * all subclass constructors must fill it; by convention, from their first argument
18
19`N->print(std::ostream&)` is a visitor now, port these methods to `ast::Print` class
20* **TODO** write this visitor
21* **TODO** write `std::ostream& operator<< ( std::ostream& out, const Node* node )` in `Node.hpp` in terms of `ast::Print`
22* `Declaration::printShort` should also be integrated
23
24`clone` is private to `Node` now
25* still needs to be overriden to return appropriate type
26  * e.g. `private: virtual Stmt* clone() const override = 0;`
27
28All leaves of the `Node` inheritance tree are now declared `final`
29* e.g. `class CompoundStmt final : public Stmt`
30* allows compiler to optimize virtual calls to static calls if given static type
31
32Pulled `FuncSpecifiers` and `StorageClasses` out of `Type` into their own headers
33* Made `BFCommon` a `MakeBitfield` macro in its own header
34  * added default and field-init constructors to macro
35
36Prefer move semantics for containers passed to node constructors
37
38## Code Style ##
39
40### Files ###
41* Headers have a `.hpp` suffix
42* Source code has a `.cpp` suffix
43* All source has the project-standard leading and trailing comments
44* prefer `#pragma once` over `#ifdef` guards
45* namespaces that cover entire files don't get indented
46
47### Documentation ###
48* class, method, and field comments should use doxygen-style `///` prefix
49  * should be included on all classes
50  * should be included on any method declaration that doesn't have an obvious behaviour from either naming convention (e.g. constructor, print operator, implement visitor pattern) or an inline implementation
51* use explanatory comments with `//` wherever appropriate
52  * older comments should be maintained in porting process wherever possible
53
54### Naming ###
55* Preserve names from previous AST whenever reasonable, and get team consensus on any changes.
56* Strong justification required for private fields
57  * No `get_` prefix on getters (including for generated fields)
58* Notable changes:
59  * for concision and consistency with subclasses:
60    * `Declaration` => `ast::Decl`
61        * `DeclarationWithType` => `ast::DeclWithType`
62        * `Expression` => `ast::Expr`
63        * `Initializer` => `ast::Init`
64    * `Statement` => `ast::Stmt`
65  * because they don't really belong to `Type` (and for consistency with `Linkage::Spec`):
66    * `Type::StorageClasses` => `ast::Storage::Classes`
67          * `Type::Extern` etc. => `ast::Storage::Extern` etc.
68        * `LinkageSpec::Spec` => `ast::Linkage::Spec`
69          * `LinkageSpec::Mangle` etc. => `ast::Linkage::Mangle` etc.
70          * `LinkageSpec::linkageUpdate` => `ast::Linkage::update`
71          * `LinkageSpec::linkageName` => `ast::Linkage::name`
72          * `LinkageSpec::isMangled(Spec)` etc. => `Spec.is_mangled` etc.
73          * `LinkageSpec::Intrinsic` etc. => `ast::Linkage::Intrinsic` etc.
74
75## Specific Nodes ##
76`Decl`
77* `storageClasses` => `storage`
78* `declFromId()` => `fromId()`
79  * not 100% sure about the return type here...
80
81`DeclWithType`
82* When `SymTab::Validate::Pass2` is rewritten, update comment on `mangleName` with new name of pass
83* `get_scopedMangleName()` => `scopedMangleName()`
84* `get_type()` now returns `const Type*` so can't be inadvertently mutated
85  * still with `get_` name so it doesn't conflict with subclass field names
86
87`ObjectDecl`
88* changed constructor parameter order for better defaults
89  * allows `newObject` as just default settings
90
91`EnumDecl`
92* **TODO** rebuild `eval` for new AST (re: `valueOf` implementation)
93
94`Expr`
95* Merged `inferParams`/`resnSlots` into union, as suggested by comment
96
97`Label`
98* `get_statement()` exclusively used for code location, replaced with `CodeLocation` field
99
100`CompoundStmt`
101* **TODO** port copy operator
102  * Needs to be an almost-shallow clone, where the declarations are cloned only if needed
103  * **TODO** port DeclReplacer
104* Still a `std::list` for children, rather than `std::vector`
105  * allows more-efficient splicing for purposes of later code generation
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