mirror of
https://github.com/ValKmjolnir/Nasal-Interpreter.git
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Valk Richard Li
115 lines
3.1 KiB
Markdown
115 lines
3.1 KiB
Markdown
# Nasal Interpreter
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[](http://wiki.flightgear.org/File:Nasallogo3.png)
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# Nasal script language
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[Nasal](http://wiki.flightgear.org/Nasal_scripting_language) is a script language that used in [FlightGear](https://www.flightgear.org/).
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There is a Nasal console in FlightGear but sometimes it is not so easy for every developer to use.
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So this is an interpreter for Nasal written by C++.
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The interpreter is still in development.We really need your support!
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# Why Writing Nasal Interpreter
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Nasal is a script language first used in Flightgear.
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But in last summer holiday, members in FGPRC told me that it is hard to debug with nasal-console in Flightgear, especially when checking syntax error.
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So i tried to write a new interpreter to help them checking syntax error and even, runtime error.
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I wrote the lexer, parser and runtime(nasal virtual machine/ast-runtime virtual machine) to help checking errors.
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They found it easier for them to check errors before copying nasal-codes in nasal-console in Flightgear to test.
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# How to Compile
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> g++ -std=c++11 main.cpp -o main.exe
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# Lexical Analysis
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The flow chart of lexer is here:
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[](https://github.com/ValKmjolnir/Nasal-Interpreter/blob/master/pic/nasal_lexer.png)
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This picture seems ugly. I will re-draw it later(maybe 1000 years later).
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# Parser
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## Version 3.0
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I refactored parser and make it easier to maintain.
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The EBNF is also refactored.
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## Version 4.0
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Parser in this version will pre-calculate some mathematical equations.
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This will make bytecode vm running more quickly.
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# Abstract Syntax Tree
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## Version 1.2
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The ast has been completed in this version.
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## Version 2.0
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A completed ast-interpreter with unfinished lib functions.
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## Version 3.0
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The ast is refactored and is now easier to read and maintain.
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Ast-interpreter uses new techniques so it can run codes more efficiently.
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Now you can add your own functions as builtin-functions in this interpreter!
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I decide to save the ast interpreter after releasing v4.0. Because it took me a long time to think and write...
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## Version 5.0
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I change my mind.AST interpreter leaves me too much things to do.
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If i continue saving this interpreter,it will be harder for me to make the bytecode vm become more efficient.
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# Byte Code Interpreter
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## Version 4.0
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I have just finished the first version of byte-code-interpreter.
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This interpreter is still in test.After this test,i will release version 4.0!
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Now i am trying to search hidden bugs in this interpreter.Hope you could help me! :)
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There's an example of byte code below:
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```javascript
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var (a,b,c)=(1,2,3);
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```
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```asm
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.number 1
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.number 2
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.number 3
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.symbol a
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.symbol b
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.symbol c
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0x00000000: pone 0x00000000
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0x00000001: load 0x00000000 (a)
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0x00000002: pnum 0x00000001 (2)
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0x00000003: load 0x00000001 (b)
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0x00000004: pnum 0x00000002 (3)
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0x00000005: load 0x00000002 (c)
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0x00000006: nop 0x00000000
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```
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## Version 5.0
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I decide to optimize bytecode vm in this version.
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Because it takes more than 1.5s to count i from 0 to 4000000-1.This is not efficient at all! |