split format/table::from_list into multiple functions

src/format/table.rs

@@ -9,13 +9,15 @@ use textwrap::fill;
 use prettytable::format::{FormatBuilder, LinePosition, LineSeparator};
 use prettytable::{color, Attr, Cell, Row, Table};
 
+type Entries = Vec<Vec<(String, &'static str)>>;
+
 #[derive(Debug, new)]
 pub struct TableView {
     // List of header cell values:
     headers: Vec<String>,
 
     // List of rows of cells, each containing value and prettytable style-string:
-    entries: Vec<Vec<(String, &'static str)>>,
+    entries: Entries,
 }
 
 enum TableMode {
@@ -50,110 +52,169 @@ impl TableView {
             return None;
         }
 
-        let mut headers = TableView::merge_descriptors(values);
-
-        if headers.is_empty() {
-            headers.push("<value>".to_string());
-        }
-
-        let mut entries = vec![];
-
-        for (idx, value) in values.iter().enumerate() {
-            let mut row: Vec<(String, &'static str)> = headers
-                .iter()
-                .map(|d| {
-                    if d == "<value>" {
-                        match value {
-                            Value {
-                                value: UntaggedValue::Row(..),
-                                ..
-                            } => (
-                                format_leaf(&UntaggedValue::nothing()).plain_string(100_000),
-                                style_leaf(&UntaggedValue::nothing()),
-                            ),
-                            _ => (format_leaf(value).plain_string(100_000), style_leaf(value)),
-                        }
-                    } else {
-                        match value {
-                            Value {
-                                value: UntaggedValue::Row(..),
-                                ..
-                            } => {
-                                let data = value.get_data(d);
-                                (
-                                    format_leaf(data.borrow()).plain_string(100_000),
-                                    style_leaf(data.borrow()),
-                                )
-                            }
-                            _ => (
-                                format_leaf(&UntaggedValue::nothing()).plain_string(100_000),
-                                style_leaf(&UntaggedValue::nothing()),
-                            ),
-                        }
-                    }
-                })
-                .collect();
-
-            if values.len() > 1 {
-                // Indices are black, bold, right-aligned:
-                row.insert(0, ((starting_idx + idx).to_string(), "Fdbr"));
-            }
-
-            entries.push(row);
-        }
-
-        let mut max_per_column = vec![];
-
-        if values.len() > 1 {
-            headers.insert(0, "#".to_owned());
-        }
-
-        for i in 0..headers.len() {
-            let mut current_col_max = 0;
-            let iter = entries.iter().take(values.len());
-
-            for entry in iter {
-                let value_length = entry[i].0.chars().count();
-                if value_length > current_col_max {
-                    current_col_max = value_length;
-                }
-            }
-
-            max_per_column.push(std::cmp::max(current_col_max, headers[i].chars().count()));
-        }
-
         // Different platforms want different amounts of buffer, not sure why
         let termwidth = std::cmp::max(textwrap::termwidth(), 20);
 
-        // Make sure we have enough space for the columns we have
-        let max_num_of_columns = termwidth / 10;
+        let mut headers = TableView::merge_descriptors(values);
+        let mut entries = values_to_entries(values, &mut headers, starting_idx);
+        let max_per_column = max_per_column(&headers, &entries, values.len());
 
-        // If we have too many columns, truncate the table
-        if max_num_of_columns < headers.len() {
-            headers.truncate(max_num_of_columns);
+        maybe_truncate_columns(&mut headers, &mut entries, termwidth);
+        let headers_len = headers.len();
 
-            for entry in &mut entries {
-                entry.truncate(max_num_of_columns);
-            }
+        // Measure how big our columns need to be (accounting for separators also)
+        let max_naive_column_width = (termwidth - 3 * (headers_len - 1)) / headers_len;
 
-            headers.push("...".to_owned());
-            for entry in &mut entries {
-                entry.push(("...".to_owned(), "c")); // ellipsis is centred
+        let column_space =
+            ColumnSpace::measure(&max_per_column, max_naive_column_width, headers_len);
+
+        // This gives us the max column width
+        let max_column_width = column_space.max_width(termwidth);
+
+        // This width isn't quite right, as we're rounding off some of our space
+        let column_space = column_space.fix_almost_column_width(
+            &max_per_column,
+            max_naive_column_width,
+            max_column_width,
+            headers_len,
+        );
+
+        // This should give us the final max column width
+        let max_column_width = column_space.max_width(termwidth);
+
+        // Wrap cells as needed
+        let table_view = wrap_cells(
+            headers,
+            entries,
+            max_per_column,
+            max_naive_column_width,
+            max_column_width,
+        );
+        Some(table_view)
+    }
+}
+
+fn values_to_entries(values: &[Value], headers: &mut Vec<String>, starting_idx: usize) -> Entries {
+    let mut entries = vec![];
+    let values_len = values.len();
+
+    if headers.is_empty() {
+        headers.push("<value>".to_string());
+    }
+
+    for (idx, value) in values.iter().enumerate() {
+        let mut row: Vec<(String, &'static str)> = headers
+            .iter()
+            .map(|d: &String| {
+                if d == "<value>" {
+                    match value {
+                        Value {
+                            value: UntaggedValue::Row(..),
+                            ..
+                        } => (
+                            format_leaf(&UntaggedValue::nothing()).plain_string(100_000),
+                            style_leaf(&UntaggedValue::nothing()),
+                        ),
+                        _ => (format_leaf(value).plain_string(100_000), style_leaf(value)),
+                    }
+                } else {
+                    match value {
+                        Value {
+                            value: UntaggedValue::Row(..),
+                            ..
+                        } => {
+                            let data = value.get_data(d);
+                            (
+                                format_leaf(data.borrow()).plain_string(100_000),
+                                style_leaf(data.borrow()),
+                            )
+                        }
+                        _ => (
+                            format_leaf(&UntaggedValue::nothing()).plain_string(100_000),
+                            style_leaf(&UntaggedValue::nothing()),
+                        ),
+                    }
+                }
+            })
+            .collect();
+
+        if values_len > 1 {
+            // Indices are black, bold, right-aligned:
+            row.insert(0, ((starting_idx + idx).to_string(), "Fdbr"));
+        }
+
+        entries.push(row);
+    }
+
+    if values_len > 1 {
+        headers.insert(0, "#".to_owned());
+    }
+
+    entries
+}
+
+fn max_per_column(headers: &Vec<String>, entries: &Entries, values_len: usize) -> Vec<usize> {
+    let mut max_per_column = vec![];
+
+    for i in 0..headers.len() {
+        let mut current_col_max = 0;
+        let iter = entries.iter().take(values_len);
+
+        for entry in iter {
+            let value_length = entry[i].0.chars().count();
+            if value_length > current_col_max {
+                current_col_max = value_length;
             }
         }
 
-        // Measure how big our columns need to be (accounting for separators also)
-        let max_naive_column_width = (termwidth - 3 * (headers.len() - 1)) / headers.len();
+        max_per_column.push(std::cmp::max(current_col_max, headers[i].chars().count()));
+    }
 
-        // Measure how much space we have once we subtract off the columns who are small enough
+    max_per_column
+}
+
+fn maybe_truncate_columns(headers: &mut Vec<String>, entries: &mut Entries, termwidth: usize) {
+    // Make sure we have enough space for the columns we have
+    let max_num_of_columns = termwidth / 10;
+
+    // If we have too many columns, truncate the table
+    if max_num_of_columns < headers.len() {
+        headers.truncate(max_num_of_columns);
+
+        for entry in &mut entries.into_iter() {
+            entry.truncate(max_num_of_columns);
+        }
+
+        headers.push("...".to_owned());
+
+        for entry in &mut entries.into_iter() {
+            entry.push(("...".to_owned(), "c")); // ellipsis is centred
+        }
+    }
+}
+
+struct ColumnSpace {
+    num_overages: usize,
+    underage_sum: usize,
+    overage_separator_sum: usize,
+}
+
+impl ColumnSpace {
+    /// Measure how much space we have once we subtract off the columns who are small enough
+    fn measure(
+        max_per_column: &[usize],
+        max_naive_column_width: usize,
+        headers_len: usize,
+    ) -> ColumnSpace {
         let mut num_overages = 0;
         let mut underage_sum = 0;
         let mut overage_separator_sum = 0;
-        let iter = max_per_column.iter().enumerate().take(headers.len());
+        let iter = max_per_column.iter().enumerate().take(headers_len);
+
         for (i, &column_max) in iter {
             if column_max > max_naive_column_width {
                 num_overages += 1;
-                if i != (headers.len() - 1) {
+                if i != (headers_len - 1) {
                     overage_separator_sum += 3;
                 }
                 if i == 0 {
@@ -162,7 +223,7 @@ impl TableView {
             } else {
                 underage_sum += column_max;
                 // if column isn't last, add 3 for its separator
-                if i != (headers.len() - 1) {
+                if i != (headers_len - 1) {
                     underage_sum += 3;
                 }
                 if i == 0 {
@@ -171,23 +232,31 @@ impl TableView {
             }
         }
 
-        // This gives us the max column width
-        let max_column_width = if num_overages > 0 {
-            (termwidth - 1 - underage_sum - overage_separator_sum) / num_overages
-        } else {
-            99999
-        };
+        ColumnSpace {
+            num_overages,
+            underage_sum,
+            overage_separator_sum,
+        }
+    }
+
+    fn fix_almost_column_width(
+        self,
+        max_per_column: &[usize],
+        max_naive_column_width: usize,
+        max_column_width: usize,
+        headers_len: usize,
+    ) -> ColumnSpace {
+        let mut num_overages = 0;
+        let mut overage_separator_sum = 0;
+        let mut underage_sum = self.underage_sum;
+        let iter = max_per_column.iter().enumerate().take(headers_len);
 
-        // This width isn't quite right, as we're rounding off some of our space
-        num_overages = 0;
-        overage_separator_sum = 0;
-        let iter = max_per_column.iter().enumerate().take(headers.len());
         for (i, &column_max) in iter {
             if column_max > max_naive_column_width {
                 if column_max <= max_column_width {
                     underage_sum += column_max;
                     // if column isn't last, add 3 for its separator
-                    if i != (headers.len() - 1) {
+                    if i != (headers_len - 1) {
                         underage_sum += 3;
                     }
                     if i == 0 {
@@ -196,7 +265,7 @@ impl TableView {
                 } else {
                     // Column is still too large, so let's count it
                     num_overages += 1;
-                    if i != (headers.len() - 1) {
+                    if i != (headers_len - 1) {
                         overage_separator_sum += 3;
                     }
                     if i == 0 {
@@ -205,25 +274,53 @@ impl TableView {
                 }
             }
         }
-        // This should give us the final max column width
-        let max_column_width = if num_overages > 0 {
-            (termwidth - 1 - underage_sum - overage_separator_sum) / num_overages
+
+        ColumnSpace {
+            num_overages,
+            underage_sum,
+            overage_separator_sum,
+        }
+    }
+
+    fn max_width(&self, termwidth: usize) -> usize {
+        let ColumnSpace {
+            num_overages,
+            underage_sum,
+            overage_separator_sum,
+        } = self;
+
+        if *num_overages > 0 {
+            (termwidth - 1 - *underage_sum - *overage_separator_sum) / *num_overages
         } else {
             99999
-        };
+        }
+    }
+}
+
+fn wrap_cells(
+    mut headers: Vec<String>,
+    mut entries: Entries,
+    max_per_column: Vec<usize>,
+    max_naive_column_width: usize,
+    max_column_width: usize,
+) -> TableView {
+    {
+        let entries = &mut entries;
 
-        // Wrap cells as needed
         for head in 0..headers.len() {
             if max_per_column[head] > max_naive_column_width {
                 headers[head] = fill(&headers[head], max_column_width);
 
-                for entry in &mut entries {
+                for entry in &mut entries.into_iter() {
                     entry[head].0 = fill(&entry[head].0, max_column_width);
                 }
             }
         }
+    }
 
-        Some(TableView { headers, entries })
+    TableView {
+        headers: headers,
+        entries: entries,
     }
 }