FANG-Xiaolin / MUA_Interpreter

An interpreter for an interpreted language

MakeUp Programming Language

This is an interpreter for a interpreted language written in JAVA. The interpreted language is called MUA(MakeUp Programming Language). The grammar of this language can be found below.

It support function defining, function calling, loop, recursive procedures, etc.

Try it by yourself! Also, Please do not borrow the code directly for course projects if your mentor does not allow you to do so. Thanks: )

Examples

1.Some basic operations

2.Define a function named f with argument a. Multi-line definition is support, which means you can define a function in multiple lines and the interpreter will try to match the brankets.

3.A more complex function. The infix expression is also supported.

4.Argument for functions can be result of an infix expression. Negative numbers supported also.

5.Double numbers and infix expression.

6.Repeat

7.Some other operations.

Grammar

fundamental data type - value

number, word, list, bool

• content of a number starts with[0~9] or -

• content of a word starts with". Anything following " before a space will be considered as part of the word, including " and []

• content of a list is wrapped with[], the elements inside are seperated by space. The elements inside can be any data type and can be different.

fundamental operation

format: op_name arguments

Different arguments are seperated by spaces.

fundamental op：

• //：comment

• make <word> <value>： bind the value to the word. The word is then called name and located in the namespace.

• thing <word>：return the value bound with word

• :<word>：the same as thing

• erase <word>：erase the value bound with word

• isname <word>：if word is a name

• print <value>：print value

• read：return a word or list read from stdin

• readlinst：return a line read from stdin and form a list

• operator

  • add, sub, mul, div, mod：<operator> <number> <number>

  • eq, gt, lt：<operator> <number|word> <number|word>

  • and, or：<operator> <bool> <bool>

  • not：not <bool>

• random <number>：return a random number between [0,number>

• sqrt <number>：return sqrt

• isnumber <value>：return bool indicating whether value is a number

• isword <value>：return bool indicating whether value is a word

• islist <value>：return bool indicating whether value is a list

• isbool <value>：return bool indicating whether value is a bool

• isempty <word|list>: return bool indicating whether word|list is empty

• test <value>：test whether value is true or false, no return value

• iftrue <list>：if the test before is true, do the list

• iffalse <list>：if the test before is false, do the list

• word <word> <word|number|bool>：merge two word into one. The second value can be word,number, or bool

• list <list1> <list2>：merge list1 and list2 in to one list, elements in list2 following those in list1

• join <list> <value>：add the [value] into the [list] as the last element

• first <word|list>：return the first character/element of word/list

• last <word|list>：return the last character/element of word/list

• butfirst <word|list>：return a list/word excepting the last element/character

• butlast <word|list>：return a list/word excepting the last element/character

• item <number> <word|list>：return the [number] character/element in a word/list

• repeat <number> <list>：run the code in [list] for [number] times

• stop：stop the execution of current code fragment(may be a piece of code in run/repeat/if/function)

• wait <number>：wait for number ms

• save <word>：save the current namespace to [word]file

• load <word>：load contents from [word]file and add to the namespace

• erall：erase all the names in current namespace

• poall：print all the names in current namespace

Function

definition

	make <word> [<list1> <list2>]

word is the function name

list1 is the arguments list, list2 is the operation list

call function

	<functionName> <arglist>

functionName is the function name defined in make. "is not needed.

arglist is the arguments list, values in arglist are correspondingly bound to the name in function definition.

related operations

• output <value>：set value as the return value to the caller. But do not stop execution of function.

• stop：stop execution

• local <word>： set the word as local name. The arguments are also local names.

Built-in name

The language provide some frequent use constants and operations as built-in name. These names can be erased also.

• pi：3.14159

• if <bool> <list1> <list2>：if bool is true, run list1, else list2. Both lists can be empty

• run <list>：run the code in the list