Compiler for Natural. Semester project in Compiler Design at Wentworth Institute of Technology Summer 2016.

To see parser output, read the ABOUT.md file located under the src/output/ directory.

Added IO to the language:

  int a
  input("Enter an integer value for a: ", a)
  print("\na = ", a)

1. Locate the Test.java file in the parser package.
2. Run the main method from that class.

All the files in the /src/test/ directory will be scanned in by the lexer and checked for syntax correctness by the parser. The files in the test/ directory beginning with E contain errors that should be found by the parser. The remaining files, all starting numbers should not display any errors when being parsed.

The syntax for the natural language is presented below.

Natural supports the following six basic data types.

• int (4-bytes)
• long (8-bytes)
• float (8-bytes)
• double (16-bytes)
• char (1-byte)
• boolean (1-byte)

Variable declaration is currently supported in the form of a single declaration per line. Each declaration should consist of a datatype and an identifier. Valid identifiers must start with an alphabetic letter.

• int integer
• long aLongNumber
• float floatingPoint
• double aDoubleFloatingPoint
• char singleCharacter
• boolean trueOrFalse

Natural supports the same comparison operators that java, c, and c++ supports but it also supports the written meanings of the operators. This is intended to make the language easy to transfer to for c, java, and c++ programmers but also allow the language to look as close to english/ pseudocode as possible. All synonomous operators are grouped together below.

Less than comparison operators

• <
• less than

Greater than comparison operators

• greater than

Less than or equal to comparison operators

• <=
• less than or equal to

Greater than or equal to comparison operator

• =

• greater than or equal to

Equality Operators

• =
• equal to
• equals

Inequality Operators

• !=
• not equal to

There are two operators for assigning variables in Natural. Variables can be assigned at the same time that they are declared.

• is
• :=

An example of assigning varivous data types to values

int a is 5
int b := 6
boolean isNatural is true
char c is 'c'
long bigNumber := 1000000000000
double real is 4.4443

Natural supports the similar joining operators as many c based languages as well as the written version of the operators.

• || (double bar for boolean or)

• or (the reserved "or" keyword can also be used for boolean or)

• && (double ampersand is used for boolean and)

• and (the keyword "and" can also be used for boolean and)

• ! (single exclamation is used for boolean negation)

• not (the reserved "not" keyword can also be used for boolean negation)

To include comments use the following:

#this is a single line comment 

##
  This is a multi
  Line 
  Comment
##

To increase / decrease values use the following reserved words:

• increase by
• decrease by

Example:

int a is 4
a increase by 1     # same as saying a is a + 1
a decrease by 1     # same as saying a is a - 1

Natural Supports the following for control flow:

• if
• else if
• else
• while
• do while
• for
• break

Example syntax:

int a is 4
if(a less than 5){
    #do something
} else if (a greater than or equal to 5){
    #do something else 
} else {
    #default case 
}

boolean aBool is true
while(aBool and a less than 6){
    
    #do something while true
    
    if (a equals 7){
      break;                      #breaks should be followed by a semicolon 
    }
}


do{
  a increase by 1
  
  if (a equals 10){
    break;
  }
  
} while (true)

for(int j is 4; j less than 10; j increase by 1){
  #loop through some code 
}