a simple and stupid compiler collection(just now for PL0, support for other languages may be added someday)
this is a compiler collection(though it just support PL0). i am trying to make it extendable by defining dozen of abstract class.
the compiler now is a two-period compiler. the recursive down parser generates parser tree and AST by calling lexer to get one token a time. then, by travling the AST, P-Codes are generated.
- Chinese identifier is supported.
- error report is detailed to line number in lexer analysis, syntax analysis. adding error erport with line number in semantic analysis is easy as long as line number is recorded in syntax tree.
- can get parse tree and syntax tree.
- debug or verbose mode for VM is supported. support for single step excute and displaying stack, instruct, register.
define AbstractLexer in Lexer/AbstractLexer.py, which has input(), hasnext(), forward(), backward().
define AbstractParser in Parser/AbstractParser.py, which has call(), parse().
define some datastruct that used commonly in each period of compiler, such as SyntaxTree for syntax analysis.
define AbstractGen in VM/AbstractGen.py, which is a interface for semantic analyzer and AbstractVM in VM/AbstractVM.py which is a interface for virtual machine.
define some class that used in lexer analyzer for PL0.
in Lexer/PL0/SimpleLexer.py define a subclass of AbstractLexer named SimpleLexer and Statement to store source code. add function next_character_safe in SimpleLexer to prevent exception when contining read whlie EOF reached. add function get_int make is simple for float detection(though it is not defined in PL0). use dict to make token analysis simple.
in Parser/PL0/RecursiveParser.py define a subclass of AbstractParser named RecursiveParser, which is a typical recursive down parser with function named in Chinese(little bit strange). instacne of this class is callable with source code(type str) as input, outputing parse tree and AST.
define a tree type struct with gencode() and print(). gencode() is designed to support semantic analysis. print() is designed for print.
in this file, define series of class with semantic meanings, such as VariableDeclaration, AssignExpression. each class defined in this file should be subclass of TreeNode.
interface gencode is implement in each class which accept two arguments: symbol table and code, returning nothing but may raise SemanticException.
in this file, define SymbolTable and PCodeGener which is a subclass of AbstractGen.
SymbolTable uses a stack based block symbol table.
instance of PCodeGener is callable with AST as input and P-Code as output. it is just create a instance of SymbolTable and a list as the container of p-Code at beginning, then use them to call AST's gencode function. the P-Code is store in the list created previously.
in this file, PCodeVM is defined, which is a subclass of AbstractVM.
constructor of PCodeVM accept some keyword argument, which indicate the VM runs in debug mode or verbose mode
instance of PCodeVM is callable, accepting a list of P-Code and excute it. using dict and higher-corder function to make it simple to implement.