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Meta processing 

- Finished describing the process of "Macro replacement"
This commit is contained in:
Tristan B. Velloza Kildaire 2023-07-09 21:33:56 +02:00
parent ea24f05e8b
commit 7155cb9b77
2 changed files with 39 additions and 1 deletions
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23
docs/implementation/38-meta.md
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@ -148,3 +148,26 @@ them with some other node (in this example an `IntegerLiteral`) which
makes sense. We make heavy use of the `MStatementSearchable` (for
**searching**) and the `MStatementReplaceable` (for **replacing**)
interfaces as part of this process.
The method of replacement is to examine the current `Statement` being
iterated on in the call to `process(Container)`, we then check the
following things:
1. Is the current statement both `MStatementSearchable` and
`MStatementReplaceable` compatible?
2. **If so**, search for all `FunctionCall` AST nodes
3. Of all the `FunctionCall` AST node(s) found:
- If the name of the function being called is `sizeof`?
- If their is only a single argument passed to said function call?
- If the argument passed is an `IdentExpression`?
4. **If the above are all true**, then we proceed to do:
- Extract the `IdentExpression`’s name field
- Pass this to `sizeOf_Literalize(string)`
- Now replace this `IdentExpression` with the `IntegerLiteral`
returned by `sizeOf_Literalize(string)`
The replacement is done from the current container, and we pass it the
`FunctionCall` (the `sizeof<type>`) we found as the first argument (what
to search for) and then the second argument is our newly created
`IntegerLiteral` which is what will replace the spot that `FunctionCall`
occupies in the AST tree.

17
docs_src/implementation/38-meta.md
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@ -115,4 +115,19 @@ This does two checks:
#### Macro replacement
To support macros such as `sizeof(<type>)` we need to be able to find where they occur and then, no matter how deep in the AST tree, replace
them with some other node (in this example an `IntegerLiteral`) which makes sense. We make heavy use of the `MStatementSearchable` (for **searching**) and the `MStatementReplaceable` (for **replacing**) interfaces as part of this process.
them with some other node (in this example an `IntegerLiteral`) which makes sense. We make heavy use of the `MStatementSearchable` (for **searching**) and the `MStatementReplaceable` (for **replacing**) interfaces as part of this process.
The method of replacement is to examine the current `Statement` being iterated on in the call to `process(Container)`, we then check the following things:
1. Is the current statement both `MStatementSearchable` and `MStatementReplaceable` compatible?
2. **If so**, search for all `FunctionCall` AST nodes
3. Of all the `FunctionCall` AST node(s) found:
* If the name of the function being called is `sizeof`?
* If their is only a single argument passed to said function call?
* If the argument passed is an `IdentExpression`?
4. **If the above are all true**, then we proceed to do:
* Extract the `IdentExpression`'s name field
* Pass this to `sizeOf_Literalize(string)`
* Now replace this `IdentExpression` with the `IntegerLiteral` returned by `sizeOf_Literalize(string)`
The replacement is done from the current container, and we pass it the `FunctionCall` (the `sizeof<type>`) we found as the first argument (what to search for) and then the second argument is our newly created `IntegerLiteral` which is what will replace the spot that `FunctionCall` occupies in the AST tree.