Preliminary code for execution

final_lang/exec.py

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+import ast
+import sys
+
+normalOperators = ['+', '-', '*', '/', '>', '<',
+                   '<=', '>=', '==', '/=', '.and.', '.or.']
+
+
+class VarTable:
+    def __init__(self):
+        self.symbols = {}
+
+    def setVar(self, direction, value):
+        realDic = 0
+        if direction[0] == '$':
+            realDic = int(direction[1:])
+        elif direction[0] == '*':
+            realDic = int(self.getVar(direction.replace('*', '$')))
+
+        self.symbols[realDic] = value
+
+    def getVar(self, direction):
+        realDic = 0
+        if direction[0] == '$':
+            realDic = int(direction[1:])
+        elif direction[0] == '*':
+            indirectDic = int(direction[1:])
+            if indirectDic in self.symbols:
+                realDic = self.symbols[indirectDic]
+            else:
+                raise Exception(f'''
+                The value at direction {indirectDic} is accessed before initialization.
+                ''')
+
+        if realDic in self.symbols:
+            return self.symbols[realDic]
+        else:
+            raise Exception(f'''
+            The value at direction {realDic} is accessed before initialization.
+            ''')
+
+
+# An instance of the [VarTable] class.
+variables = VarTable()
+
+
+def isDirection(operand):
+    if type(operand) is not str:
+        return False
+    if len(operand) > 1 and (operand[0] == '$' or operand[0] == '*'):
+        return True
+    return False
+
+
+def isStringLiteral(string):
+    return string[0] == '\'' and string[len(string) - 1] == '\''
+
+
+def splitQuad(string):
+    result = []
+    buffer = ''
+    isStringOpen = False
+    skip = False
+    tokens = string.split()
+    for token in tokens:
+        if isStringOpen:
+            buffer += ' '
+            buffer += token
+            if token[len(token) - 1] == '\'':
+                result.append(buffer)
+                isStringOpen = False
+        else:
+            if token[0] == '\'':
+                if token[len(token) - 1] == '\'':
+                    result.append(token)
+                else:
+                    buffer = token
+                    isStringOpen = True
+            else:
+                result.append(token)
+    return result
+
+
+def evalOperation(operator, operand1, operand2):
+    value1 = 0
+    value2 = 0
+    if isDirection(operand1):
+        value1 = variables.getVar(operand1)
+    else:
+        value1 = ast.literal_eval(operand1)
+
+    if isDirection(operand2):
+        value2 = variables.getVar(operand2)
+    else:
+        value2 = ast.literal_eval(operand2)
+
+    if operator == '+':
+        return value1 + value2
+    elif operator == '-':
+        return value1 - value2
+    elif operator == '*':
+        return value1 * value2
+    elif operator == '/':
+        return value1 / value2
+    elif operator == '>':
+        return value1 > value2
+    elif operator == '<':
+        return value1 < value2
+    elif operator == '>=':
+        return value1 >= value2
+    elif operator == '<=':
+        return value1 <= value2
+    elif operator == '==':
+        return value1 == value2
+    elif operator == '/=':
+        return value1 != value2
+    elif operator == '.and.':
+        return value1 and value2
+    elif operator == '.or.':
+        return value1 or value2
+
+
+def execute(quads):
+    # Index of the quadruplet currently being executes.
+    currentQuad = 1
+
+    while currentQuad <= len(quads):
+        tokens = splitQuad(quads[currentQuad - 1])
+        # ---------- print operation
+        if tokens[0] == 'print':
+            if tokens[1] == 'endline':
+                # adding a new line
+                print('')
+            elif isStringLiteral(tokens[1]):
+                print(tokens[1].replace('\'', ''), end='')
+            else:
+                value = variables.getVar(tokens[1])
+                print(value, end='')
+        # ---------- read operation
+        elif tokens[0] == 'read':
+            value = input()
+            variables.setVar(tokens[1], ast.literal_eval(value))
+        # ---------- arithmetic and logical operations
+        elif tokens[0] in normalOperators:
+            result = evalOperation(tokens[0], tokens[1], tokens[2])
+            variables.setVar(tokens[3], result)
+        # ---------- assign operation
+        elif tokens[0] == '=':
+            newValue = 0
+            if isDirection(tokens[1]):
+                newValue = variables.getVar(tokens[1])
+            else:
+                newValue = ast.literal_eval(tokens[1])
+            variables.setVar(tokens[2], newValue)
+        # ---------- .not. operation
+        elif tokens[0] == '.not.':
+            value = variables.getVar(tokens[1])
+            variables.setVar(tokens[2], not value)
+        # ---------- gotoF operation
+        elif tokens[0] == 'gotoF':
+            value = variables.getVar(tokens[1])
+            if value == False:
+                currentQuad = int(tokens[2])
+                continue
+        # ---------- gotoF operation
+        elif tokens[0] == 'goto':
+            currentQuad = int(tokens[1])
+            continue
+        currentQuad += 1
+
+
+if (len(sys.argv) > 1):
+    programName = sys.argv[1]
+    programFile = open(programName, "r")
+    quads = programFile.readlines()
+    quads = list(map(lambda quad: quad.replace('\n', ''), quads))
+    execute(quads)
+    programFile.close()
+
+else:
+    raise Exception('''
+    No file name was provided.
+    Please add the file name as a command line argument
+
+    Example: exec.py test.fort.out
+    ''')