Programming Assignment
Implement a lexical and syntax analyzer based on the following grammar. Your analyzer should read an input test program from a file and then determine if it contains a syntax error. It does not have to show where the syntax error occurs or what kind of error it is.
→ begin end
→ {;}
→ |
→ =
→ identifier (An identifier is a string that begins with a letter followed by 0 or more letters and/or digits)
→ { (+|-) }
→ loop ()
® (< | >) (Assume that logic expressions have only less than or greater than operators)
Use the examples below to test your analyzer.
Input program with no syntax errors:
begin
total = var1 + var2;
loop (var1 < var2)
loop ( var3 > var4)
var2 = var2 - var1
end
Input programs containing syntax errors:
total = var1 + var2;
loop (var1 < var2)
loop ( var3 > var4)
var2 = var2 - var1
end
begin
total = var1 + var2;
loop (var1 < var2)
loop ( var3 > var4)
var2 = var2 - var1;
end
The keyword begin is missing.
The last statement shouldn't end with a semicolon.
begin
total = var1 + var2;
lop (var1 < var2)
var2 = var2 - var1
end
The keyword loop is misspelled.