https://github.com/yhirose/monkey-cpp

An interpreter for the Monkey programming language written in C++
https://github.com/yhirose/monkey-cpp

cpp interpret peg programing-language

Last synced: 2 months ago
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An interpreter for the Monkey programming language written in C++

• Host: GitHub
• URL: https://github.com/yhirose/monkey-cpp
• Owner: yhirose
• License: mit
• Created: 2020-03-02T21:59:36.000Z (over 4 years ago)
• Default Branch: master
• Last Pushed: 2023-07-12T02:15:22.000Z (about 1 year ago)
• Last Synced: 2024-07-10T16:04:08.300Z (3 months ago)
• Topics: cpp, interpret, peg, programing-language
• Language: C++
• Size: 552 KB
• Stars: 25
• Watchers: 3
• Forks: 4
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

• awesomecpp - Monkey - - C++ version monkey language interpreter. (Scripts)

README

        
# monkey

Another implementation of Monkey programming language described in [Writing An Interpreter In Go](https://interpreterbook.com/) and [Writing A Compiler In Go](https://compilerbook.com/).

This is written in C++ and uses [cpp-peglib](https://github.com/yhirose/cpp-peglib) PEG library for lexter and parser.

In addition to the original Monkey language spec, this implementation supports the line comment. Macro system in Appendix A is not implemented, yet.

## Install

```bash

$ git clone --recursive https://github.com/yhirose/monkey-cpp.git

$ cd monkey-cpp && mkdir build && cd build

$ cmake ..

$ make

$ ./build/cli/monkey

>> puts("hello " + "world!")

hello world!

null

>> quit

$ ./build/cli/monkey ../examples/map.monkey

[2, 4, 6, 8]

15

```

## PEG grammar

```

PROGRAM                <-  STATEMENTS

STATEMENTS             <-  (STATEMENT ';'?)*

STATEMENT              <-  ASSIGNMENT / RETURN / EXPRESSION_STATEMENT

ASSIGNMENT             <-  'let' IDENTIFIER '=' EXPRESSION

RETURN                 <-  'return' EXPRESSION

EXPRESSION_STATEMENT   <-  EXPRESSION

EXPRESSION             <-  INFIX_EXPR(PREFIX_EXPR, INFIX_OPE)

INFIX_EXPR(ATOM, OPE)  <-  ATOM (OPE ATOM)* {

                             precedence

                               L == !=

                               L < >

                               L + -

                               L * /

                           }

IF                     <-  'if' '(' EXPRESSION ')' BLOCK ('else' BLOCK)?

FUNCTION               <-  'fn' '(' PARAMETERS ')' BLOCK

PARAMETERS             <-  LIST(IDENTIFIER, ',')

BLOCK                  <-  '{' STATEMENTS '}'

CALL                   <-  PRIMARY (ARGUMENTS / INDEX)*

ARGUMENTS              <-  '(' LIST(EXPRESSION, ',') ')'

INDEX                  <-   '[' EXPRESSION ']'

PREFIX_EXPR            <-  PREFIX_OPE* CALL

PRIMARY                <-  IF / FUNCTION / ARRAY / HASH / INTEGER / BOOLEAN / NULL / IDENTIFIER / STRING / '(' EXPRESSION ')'

ARRAY                  <-  '[' LIST(EXPRESSION, ',') ']'

HASH                   <-  '{' LIST(HASH_PAIR, ',') '}'

HASH_PAIR              <-  EXPRESSION ':' EXPRESSION

IDENTIFIER             <-  < [a-zA-Z]+ >

INTEGER                <-  < [0-9]+ >

STRING                 <-  < ["] < (!["] .)* > ["] >

BOOLEAN                <-  'true' / 'false'

NULL                   <-  'null'

PREFIX_OPE             <-  < [-!] >

INFIX_OPE              <-  < [-+/*<>] / '==' / '!=' >

KEYWORD                <-  'null' | 'true' | 'false' | 'let' | 'return' | 'if' | 'else' | 'fn'

LIST(ITEM, DELM)       <-  (ITEM (~DELM ITEM)*)?

LINE_COMMENT           <-  '//' (!LINE_END .)* &LINE_END

LINE_END               <-  '\r\n' / '\r' / '\n' / !.

%whitespace            <-  ([ \t\r\n]+ / LINE_COMMENT)*

%word                  <-  [a-zA-Z]+

```