expresol

Expresol is a library for executing customizable script-languages in python. The expresol library contains two main components, the memory and the parser, which collectively work as an information system whose data is accessible via statements that manipulate stored variables when executed. Each statement is converted to an executable form containing hierarchical sets of operators and data. Each set contains a set of elements, corresponding to either variables or operators. The most common possible structure of a valid statement is as follows:

(a + b)

containing three elements, 'a', '+' and 'b', where the middle element denotes an operator and the rest denote variables.

The second possible structure is:

(~ a)

containing two elements, '~' and 'a', where The left symbol denotes an operator and the right denotes a variable.

The last possible structure is:

(a)

where 'a' denotes a variable. The identity function is assigned by default if no operator is present, meaning the output of this statement simply returns the value of 'a'.

Example

• Import library and create memory with 10 elements

    from expresol import *
    memory = Memory(10)
  

• Store functions, data, and syntax markers in memory

    memory.var(0, Marker('open'))
    memory.var(1, Marker('close'))
    memory.var(2, Marker('end'))
    memory.var(3, AND)
    memory.var(4, True)
    memory.var(5, True)
  

• Assign symbols to elements that allow data to be accessed when observed in a statement

    memory.ref(0, '(', 'grammar')
    memory.ref(1, ')', 'grammar')
    memory.ref(2, ';', 'grammar')
    memory.ref(3, '&', 'operator')
    memory.ref(4, 'x1', 'data')
    memory.ref(5, 'x2', 'data')
  

• Create parser and store data types with characters that are used to form valid symbols for instances of each type

    parser = Parser()
    parser.type('grammar', '();')
    parser.type('operator', '&|!+-*/=')
    parser.type('number', '1234567890')
    parser.type('data', 'abcdefghijklmnopqrstuvwxyz')
  

• Store pairs of data types that reflect the valid transitions between consecutive elements in a statement

    parser.rule('operator','operator')
    parser.rule('grammar','none')
    parser.rule('none','grammar')
    parser.rule('data','number')
    parser.rule('data','data')
  

• Define and execute statement

    statement = "(x1 & x2);"
    output = parser(statement, memory)
  

OUTPUT: True