I am building a calculator with Chevrotain parser and I have played with their calculator example
Chevrotain Playground: https://chevrotain.io/playground/
Parser Grammar: Calculator embedded semantics
Input Sample: Parenthesis precedence
The example above uses integer as input/output. I would like to support integers AND arrays.
Basic example:
2 * ( 3 + 7 )
Example with arrays:
2 * ( {{array1}} + {{array2}} )
const map = {
array1: [1, 2, 3, 4, 5],
array2: [10, 20, 30, 40, 50]
}
I know how to lex and parse {{array}} but I don't know how to visit them or loop over the arrays to achieve the following result
2 * ( 1 + 10 ) = 22
2 * ( 2 + 20 ) = 44
2 * ( 3 + 30 ) = 66
2 * ( 4 + 40 ) = 88
2 * ( 5 + 50 ) = 110
End result of the parsing of 2 * ( {{array1}} + {{array2}} )
should be [22, 44, 66, 88, 110]
Once the AST has been created (including the arrays on some leaf node), how can I reduce it to the end result which is an array
One approach is to have some sort of state (with the current index) and run the visitor as many time as array.length. But it is unclear to me how to can be implemented with Chevretain
This solution will work
const map = {
array1: [1, 2, 3, 4, 5],
array2: [10, 20, 30, 40, 50]
}
const { array1, array2 } = map;
const res = [];
for (let i = 0; i < (array1.length > array2.length ? array1.length : array2.length); i++) {
if (array1[i] && array2[i]) {
res.push((array1[i] + array2[i]) * 2);
} else if (array1[i] && !array2[i]) {
res.push(array1[i] * 2);
} else {
res.push(array1[i] * 2);
}
}
// res = [ 22, 44, 66, 88, 110 ]First, we will extract the arrays from an object, then we will create a loop that will run several times of the longer array (trinary operator). Inside the loop, we will insert the item from array1 plus the item from array2 doubled by 2 into the new array, and if there is no item in one of the spots in the arrays (meaning that one of the arrays is shorter than the other) we will insert only one item.