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73 lines
2.5 KiB
Markdown
73 lines
2.5 KiB
Markdown
# toy_parser.h
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This header defines the structure `Toy_Parser` which, after being initialized with a `Toy_Lexer` produces a series of abstract syntax trees to be passed to the `Toy_Compiler`. The following is a utility function provided by [repl_tools.h](repl_tools_h.md), demonstrating how to use the parser.
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```c
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//generate bytecode from a given string
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const unsigned char* Toy_compileString(const char* source, size_t* size) {
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//declare the relevant instances
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Toy_Lexer lexer;
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Toy_Parser parser;
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Toy_Compiler compiler;
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//initialize each of them
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Toy_initLexer(&lexer, source);
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Toy_initParser(&parser, &lexer);
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Toy_initCompiler(&compiler);
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//when the parser returns NULL, it is finished
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Toy_ASTNode* node = Toy_scanParser(&parser);
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while(node != NULL) {
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//if the parser returns an error node, clean up and exit gracefully
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if (node->type == TOY_AST_NODE_ERROR) {
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Toy_freeASTNode(node);
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Toy_freeCompiler(&compiler);
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Toy_freeParser(&parser);
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//no need to clean the lexer
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return NULL;
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}
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//write the node to the compiler
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Toy_writeCompiler(&compiler, node);
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Toy_freeASTNode(node);
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//grab the next node
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node = Toy_scanParser(&parser);
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}
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//get the bytecode to be returned
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const unsigned char* tb = Toy_collateCompiler(&compiler, size);
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//cleanup
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Toy_freeCompiler(&compiler);
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Toy_freeParser(&parser);
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//no need to clean the lexer
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//finally
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return tb;
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}
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```
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## Defined Functions
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### void Toy_initParser(Toy_Parser* parser, Toy_Lexer* lexer)
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This function initializes a `Toy_Parser`, binding the given `Toy_Lexer` to it.
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### void Toy_freeParser(Toy_Parser* parser)
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This function frees a `Toy_Parser` once its task is completed.
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### Toy_ASTNode* Toy_scanParser(Toy_Parser* parser)
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This function returns an abstract syntax tree representing part of the program, or an error node. The abstract syntax tree must be passed to `Toy_writeCompiler` and/or `Toy_freeASTNode`.
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This function should be called repeatedly until it returns `NULL`, indicating the end of the program.
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### void Toy_freeASTNode(Toy_ASTNode* node)
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This function cleans up any valid instance of `Toy_ASTNode` pointer passed to it. It is most commonly used to clean up the values returned by `Toy_scanParser`, after they have been passsed to `Toy_writeCompiler`, or when the node is an error node.
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Note: this function is *actually* defined in toy_ast_node.h, but documented here, because this is where it matters most.
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