Difference between revisions of "PLC Laboratory 2"
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== Lexical analyzer == | == Lexical analyzer == | ||
| − | Write a program, that reads an input and converts it into a sequence of lexical symbols – tokens. Each token composes from a type and possibly a value. | + | Write a program, that reads an input and converts it into a sequence of lexical symbols – ''tokens''. Each token is a pair, it composes from a type and possibly a value. |
The tokens definition depends on you, and it is considered a part of the solution. | The tokens definition depends on you, and it is considered a part of the solution. | ||
| Line 16: | Line 16: | ||
Symbols can be separated by a sequence of spaces, tabs, and line breaks. | Symbols can be separated by a sequence of spaces, tabs, and line breaks. | ||
| − | Notes are preceded by a sequence <code>//</code> and continue to the end of the line. | + | There can be notes in the input. Notes are preceded by a sequence <code>//</code> and continue to the end of the line. |
| + | |||
| + | ''White spaces and notes does not produce any lexical symbols.'' | ||
== Output specification == | == Output specification == | ||
| Line 26: | Line 28: | ||
<syntaxhighlight lang="haskell" > | <syntaxhighlight lang="haskell" > | ||
-2 + (245 div 3); // note | -2 + (245 div 3); // note | ||
| − | 2 mod 3 | + | 2 mod 3 * hello |
</syntaxhighlight > | </syntaxhighlight > | ||
| Line 32: | Line 34: | ||
''Your output can be different, it depends on your definition of tokens.'' | ''Your output can be different, it depends on your definition of tokens.'' | ||
<syntaxhighlight lang="haskell" > | <syntaxhighlight lang="haskell" > | ||
| + | OP:- | ||
| + | NUM:2 | ||
OP:+ | OP:+ | ||
| − | |||
| − | |||
LPAR | LPAR | ||
NUM:245 | NUM:245 | ||
DIV | DIV | ||
NUM:3 | NUM:3 | ||
| − | + | RPAR | |
SEMICOLON | SEMICOLON | ||
NUM:2 | NUM:2 | ||
MOD | MOD | ||
NUM:3 | NUM:3 | ||
| + | OP:* | ||
| + | ID:hello | ||
</syntaxhighlight > | </syntaxhighlight > | ||
Latest revision as of 10:27, 14 February 2022
Lexical analyzer
Write a program, that reads an input and converts it into a sequence of lexical symbols – tokens. Each token is a pair, it composes from a type and possibly a value.
The tokens definition depends on you, and it is considered a part of the solution.
Input specification
The input may be containing the following symbols:
- identifiers - consisting of a sequence of letters and numbers starting with a letter
- numbers - formed by a sequence of decimal digits
- operators - symbols
'+', '-', '*' and '/', - delimiters - symbols
'(', ')' and ';', - keywords -
divandmod.
Symbols can be separated by a sequence of spaces, tabs, and line breaks.
There can be notes in the input. Notes are preceded by a sequence // and continue to the end of the line.
White spaces and notes does not produce any lexical symbols.
Output specification
Converts the given input into a sequence of tokens and write them on output. Write each token on a separated line.
Example
- Input
-2 + (245 div 3); // note
2 mod 3 * hello
- Output
Your output can be different, it depends on your definition of tokens.
OP:-
NUM:2
OP:+
LPAR
NUM:245
DIV
NUM:3
RPAR
SEMICOLON
NUM:2
MOD
NUM:3
OP:*
ID:hello
