Move code into folders for convenience

This commit is contained in:
Danila Fedorin 2019-08-06 13:53:46 -07:00
parent 914b93989c
commit 34e967f364
8 changed files with 17 additions and 18 deletions

5
code/compiler/02/compile.sh Executable file
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@ -0,0 +1,5 @@
bison -o parser.cpp -d parser.y
flex -o scanner.cpp scanner.l
g++ -c -o scanner.o scanner.cpp
g++ -c -o parser.o parser.cpp
g++ main.cpp parser.o scanner.o

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@ -1,5 +1,5 @@
#include "compiler_ast.hpp"
#include "compiler_parser.hpp"
#include "ast.hpp"
#include "parser.hpp"
void yy::parser::error(const std::string& msg) {
std::cout << "An error occured: " << std::endl;

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@ -1,8 +1,8 @@
%{
#include <string>
#include <iostream>
#include "compiler_ast.hpp"
#include "compiler_parser.hpp"
#include "ast.hpp"
#include "parser.hpp"
std::vector<definition_ptr> program;
extern yy::parser::symbol_type yylex();

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@ -2,8 +2,8 @@
%{
#include <iostream>
#include "compiler_ast.hpp"
#include "compiler_parser.hpp"
#include "ast.hpp"
#include "parser.hpp"
#define YY_DECL yy::parser::symbol_type yylex()

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@ -201,7 +201,7 @@ So, our two regular expressions will be `[a-z][a-zA-Z]*` for the lowercase varia
this, we create a new file, `scanner.l`, in which we write a mix of regular expressions
and C++ code. Here's the whole thing:
{{< rawblock "compiler_scanner.l" >}}
{{< rawblock "compiler/01/scanner.l" >}}
A flex file starts with options. I set the `noyywrap` option, which disables a particular
feature of flex that we won't use, and which causes linker errors. Next up,

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@ -225,14 +225,14 @@ Just like with tokenizing, there exists a piece of software that will generate a
It's called Bison, and it is frequently used with Flex. Before we get to bison, though, we need to pay a debt we've already
incurred - the implementation of our AST. Such a tree is language-specific, so Bison doesn't generate it for us. Here's what
I came up with:
{{< codeblock "C++" "compiler_ast.hpp" >}}
{{< codeblock "C++" "compiler/02/ast.hpp" >}}
We create a base class for an expression tree, which we call `ast`. Then, for each possible syntactic construct in our language
(a number, a variable, a binary operation, a case expression) we create a subclass of `ast`. The `ast_case` subclass
is the most complex, since it must contain a list of case expression branches, which are a combination of a `pattern` and
another expression.
Finally, we get to writing our Bison file, `parser.y`. Here's what I come up with:
{{< rawblock "compiler_parser.y" >}}
{{< rawblock "compiler/02/parser.y" >}}
There's a few things to note here. First of all, the __parser__ is the "source of truth" regarding what tokens exist in our language.
We have a list of `%token` declarations, each of which corresponds to a regular expression in our scanner.
@ -260,7 +260,7 @@ to return `yy::parser::symbol_type`. You can see it in our forward declaration o
Now that we made these changes, it's time to hook up Flex to all this. Here's a new version
of the Flex scanner, with all necessary modifications:
{{< rawblock "compiler_scanner_bison.l" >}}
{{< rawblock "compiler/02/scanner.l" >}}
The key two ideas are that we overrode the default signature of `yylex` by changing the
`YY_DECL` preprocessor variable, and used the `yy::parser::make_<TOKEN>` functions
@ -268,16 +268,10 @@ to return the `symbol_type` rather than `int`.
Finally, let's get a main function so that we can at least check for segmentation faults
and other obvious mistakes:
{{< codeblock "C++" "compiler_main.cpp" >}}
{{< codeblock "C++" "compiler/02/main.cpp" >}}
Now, we can compile and run the code:
```
flex -o compiler_scanner.cpp compiler_scanner_bison.l
bison -o compiler_parser.cpp -d compiler_parser.y
g++ -c -o scanner.o compiler_scanner.cpp
g++ -c -o parser.o compiler_parser.cpp
g++ compiler_main.cpp parser.o scanner.o
```
{{< codeblock "Bash" "compiler/02/compile.sh" >}}
We used the `-d` option for Bison to generate the `compiler_parser.hpp` header file,
which exports our token declarations and token creation functions, allowing
us to use them in Flex.