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Support literal numbers with explicit plus sign (#633) #640

Merged
merged 4 commits into from
Nov 10, 2022
Merged

Support literal numbers with explicit plus sign (#633) #640

merged 4 commits into from
Nov 10, 2022

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volsa
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@volsa volsa commented Nov 8, 2022

Hi, #633 looked like a beginner friendly issue so I thought I'd give it a shot; the PR should be hopefully OK :)

Fixes issue #633 where previously the compiler would
yield an error if it encountered a number with an
explicit plus sign, i.e. the following was previously
not supported but is now
```
foo : DINT := +2147483647;
```
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codecov-commenter commented Nov 9, 2022

Codecov Report

Base: 93.76% // Head: 93.76% // Increases project coverage by +0.00% 🎉

Coverage data is based on head (87b6040) compared to base (35842fa).
Patch coverage: 76.47% of modified lines in pull request are covered.

Additional details and impacted files
@@           Coverage Diff           @@
##           master     #640   +/-   ##
=======================================
  Coverage   93.76%   93.76%           
=======================================
  Files          46       46           
  Lines       17604    17620   +16     
=======================================
+ Hits        16506    16522   +16     
  Misses       1098     1098           
Impacted Files Coverage Δ
src/parser/expressions_parser.rs 94.60% <76.47%> (+0.11%) ⬆️

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hi @volsa, thx for the PR!
the check-style-step of the build failed, you can fix the formatting via: cargo fmt

PROGRAM exp
x : DINT := 1;
y : DINT := +1;
END_PROGRAM
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this ST-code is not 100% correct. it should maybe look like this:

PROGRAM exp
   VAR
      x : INT;
   END_VAR
   x := 1;
   x := +1;
END_PROGRAM

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Out of curiosity, would the following ST-code also be wrong because it's missing a VAR block?

PROGRAM exp 
x := NULL;
END_PROGRAM

(taken from the assignment_to_null() test)

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Out of curiosity, would the following ST-code also be wrong because it's missing a VAR block?

PROGRAM exp 
x := NULL;
END_PROGRAM

(taken from the assignment_to_null() test)

so technically this works, if x is declared somewhere as a global variable. When we do parse tests, we often dont have semantically correct cases: (e.g. we dont care if x would resolve to something meaningful or not).
your sourcode mixed a statement and a declaration, you cannot have declarations outside of VAR-blocks.

I was really surprised that the parser actually returned something 😄 . but if you look at your assignment, the parser created something very strange:
Assignment{ left: "DINT", right: "1" }

so the parser thought that DINT is an identifer to a variable.

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Yeah that makes sense, thanks for clarifying.

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riederm commented Nov 9, 2022

I did some experiments and it looks like this code only covers behavior for literals. Can we also fix & test the behavior for reference?

like: ? x := +x;. I know it does nothing, but we should be able to parse it. I think this would just require a small tweak in

fn parse_unary_expression(lexer: &mut ParseSession) -> AstStatement {
let operator = match lexer.token {
OperatorNot => Some(Operator::Not),
OperatorMinus => Some(Operator::Minus),
OperatorAmp => Some(Operator::Address),
_ => None,
};
to also allow the plus sign.

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volsa commented Nov 9, 2022

Done! Fingers crossed the style-checker doesn't throw an error :P

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very nice, thx! 👍

@riederm riederm merged commit 3a76564 into PLC-lang:master Nov 10, 2022
@riederm riederm mentioned this pull request Nov 10, 2022
@volsa volsa deleted the 633-literal-numbers-with-plus-sign branch November 10, 2022 14:17
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3 participants