UPDATE: Introducing Arrays

# This PR introduces:

## Parsing arrays:

{1,2,3} and {1;2;3}

Note that array elements can be numbers, booleans and errors (#VALUE!)

## Evaluating arrays in the SUM function

=SUM({1,2,3}) works!

## Evaluating arithmetic operation with arrays

=SUM({1,2,3} * 8) or =SUM({1,2,3}+{2,4,5}) works

This is done with just one function (handle_arithmetic) for most operations

## Some mathematical functions implement arrays

=SUM(SIN({1,2,3})) works

This is done with macros. See fn_single_number
So that implementing new functions that supports array are easy


# Not done in this PR

## Most functions are not supporting arrays

When that happens we either through #N/IMPL! (not implemented error)
or do implicit intersection. Some functions will be rather trivial to "arraify" some will be hard

## The final result in a cell cannot be an array

The formula ={1,2,3} in a cell will result in #N/IMPL!

## Exporting arrays to Excel might not work correctly

Excel uses the cm (cell metadata) for formulas that contain dynamic arrays.
Although the present PR does not introduce dynamic arrays some formulas like =SUM(SIN({1,2,3}))
is considered a dynamic formula

## There are not a lot of tests in this delivery

The bulk of the tests will be added once we start going function by function# This PR introduces:

## Parsing arrays:

{1,2,3} and {1;2;3}

Note that array elements can be numbers, booleans and errors (#VALUE!)

## Evaluating arrays in the SUM function

=SUM({1,2,3}) works!

## Evaluating arithmetic operation with arrays

=SUM({1,2,3} * 8) or =SUM({1,2,3}+{2,4,5}) works

This is done with just one function (handle_arithmetic) for most operations

## Some mathematical functions implement arrays

=SUM(SIN({1,2,3})) works

This is done with macros. See fn_single_number
So that implementing new functions that supports array are easy


# Not done in this PR

## Most functions are not supporting arrays

When that happens we either through #N/IMPL! (not implemented error)
or do implicit intersection. Some functions will be rather trivial to "arraify" some will be hard

## The final result in a cell cannot be an array

The formula ={1,2,3} in a cell will result in #N/IMPL!

## Exporting arrays to Excel might not work correctly

Excel uses the cm (cell metadata) for formulas that contain dynamic arrays.
Although the present PR does not introduce dynamic arrays some formulas like =SUM(SIN({1,2,3}))
is considered a dynamic formula

## There are not a lot of tests in this delivery

The bulk of the tests will be added once we start going function by function

## The array parsing does not respect the locale

Locales that use ',' as a decimal separator need to use something different for arrays

## The might introduce a small performance penalty

We haven't been benchmarking, and having closures for every arithmetic operation and every function
evaluation will introduce a performance hit. Fixing that in he future is not so hard writing tailored
code for the operation

xlsx/src/import/worksheets.rs

@@ -808,8 +808,9 @@ pub(super) fn load_sheet<R: Read + std::io::Seek>(
         // r: reference. A1 style
         // s: style index
         // t: cell type
-        // Unused attributes
-        // cm (cell metadata), ph (Show Phonetic), vm (value metadata)
+        // cm: cell metadata (used for dynamic arrays)
+        // vm: value metadata (used for #SPILL! and #CALC! errors)
+        // ph: Show Phonetic, unused
         for cell in row.children() {
             let cell_ref = get_attribute(&cell, "r")?;
             let column_letter = get_column_from_ref(cell_ref);
@@ -825,6 +826,8 @@ pub(super) fn load_sheet<R: Read + std::io::Seek>(
                 None
             };
 
+            let cell_metadata = cell.attribute("cm");
+
             // type, the default type being "n" for number
             // If the cell does not have a value is an empty cell
             let cell_type = match cell.attribute("t") {
@@ -934,13 +937,16 @@ pub(super) fn load_sheet<R: Read + std::io::Seek>(
                             }
                         }
                     }
-                    "array" => {
-                        return Err(XlsxError::NotImplemented("array formulas".to_string()));
-                    }
                     "dataTable" => {
                         return Err(XlsxError::NotImplemented("data table formulas".to_string()));
                     }
-                    "normal" => {
+                    "array" | "normal" => {
+                        let is_dynamic_array = cell_metadata == Some("1");
+                        if formula_type == "array" && !is_dynamic_array {
+                            // Dynamic formulas in Excel are formulas of type array with the cm=1, those we support.
+                            // On the other hand the old CSE formulas or array formulas are not supported in IronCalc for the time being
+                            return Err(XlsxError::NotImplemented("array formulas".to_string()));
+                        }
                         // Its a cell with a simple formula
                         let formula = fs[0].text().unwrap_or("").to_string();
                         let context = format!("{}!{}", sheet_name, cell_ref);