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Improving Lesson 1.3 by mentioning longest match while scanning tokens #3618

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Sep 5, 2023
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Improving Lesson 1.3 by mentioning longest match while scanning tokens #3618

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Improving Lesson 1.3 by mentioning longest match while scanning tokens
Robertorosmaninho Sep 4, 2023
f17c5ec
Update README.md
Robertorosmaninho Sep 5, 2023
361d14c
Merge branch 'develop' into add-lex-erexplanation-to-tutorial
rv-jenkins Sep 5, 2023
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7 changes: 7 additions & 0 deletions k-distribution/k-tutorial/1_basic/03_parsing/README.md
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Expand Up @@ -88,6 +88,13 @@ interprets terms according to the grammar defined by the developer. It is
automatically converted into an AST of that term, and then the `colorOf`
function is evaluated using the function rules provided in the definition.

You can ask yourself: How does K match the strings between the double quotes?
The answer is that K uses Flex to generate a scanner for the grammar. Flex looks
for the longest possible match of a regular expression in the input. If there
are ambiguities between 2 or more regular expressions, it will pick the one with
the max precedence token. You can learn more about how Flex matching works
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"prec attribute", not "precedence token"

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Done!

[here](https://westes.github.io/flex/manual/Matching.html#Matching).

Bringing us back to the file `lesson-03-a.k`, we can see that this grammar
has given a simple BNF grammar for expressions over Booleans. We have defined
constructors corresponding to the Boolean values true and false, and functions
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