Minimum table width parm for shrinkwrap!

README.md

@@ -30,6 +30,8 @@ Most features of Tabulo are found in Tablo
 - Set fixed column widths, then either wrap or truncate the overflow.
 - Alternatively, shrinkwrap the table so that each column is just wide enough for its contents.
 - Put an upper limit on total table width when shrinkwrapping, to stop it overflowing your terminal horizontally.
+- Put a lower limit on total table width when shrinkwrapping, to keep table
+  width from being too small.
 - Alignment of cell content is configurable, but has helpful content-based defaults (numbers right, strings left).
 - Headers are repeatable.
 - Newlines within cell content are correctly handled.
@@ -411,7 +413,10 @@ _Take care, however, because the width of columns is then adjusted to their
 content, regardless of their width (fixed or default): so columns may be
 narrowed or widened!_
 
-If table width gets too wide, there is fortunately a workaround : just pass an argument to _shrinkwrap!_ to limit the total width of the table.
+If table width gets too wide, there is fortunately a workaround : just pass an
+argument to _shrinkwrap!_ to limit the total width of the table (or, if table
+width is too small, pass this argument as a negative value to force a minimum
+table width).
 
 ```crystal
 21: table.shrinkwrap!

spec/table_spec.cr

@@ -764,9 +764,26 @@ describe "Tablo::Table" do
            +---+-------+------+-------+-------+------+------+).gsub(/^ +/m, "")
       end
 
+      t22b = add_columns_7m(mktable_5i32(default_header_alignment: Tablo::Justify::Center, default_column_width: 8))
+      it "honors the minimum table width (negative value) passed to shrinkwrap!" do
+        t22b.shrinkwrap!(-80)
+
+        t22b.to_s.should eq \
+          %q(+----------+----------+----------+----------+----------+------------+----------+
+              |     N    |  Double  |   to_s   |   Is it  |    dec   |    word    |   cool   |
+              |          |          |          |   even?  |          |     yep    |          |
+              +----------+----------+----------+----------+----------+------------+----------+
+              |        1 |        2 | 1        |   false  |      1.0 | ww         |          |
+              |        2 |        4 | 2        |   true   |     2.00 | wwww       |          |
+              |        3 |        6 | 3        |   false  |    3.000 | wwwwww     | two      |
+              |          |          |          |          |          |            | lines    |
+              |        4 |        8 | 4        |   true   |   4.0000 | wwwwwwww   |          |
+              |        5 |       10 | 5        |   false  |  5.00000 | wwwwwwwwww |          |
+              +----------+----------+----------+----------+----------+------------+----------+).gsub(/^ +/m, "")
+      end
       t23a = add_columns_7m(mktable_5i32(default_header_alignment: Tablo::Justify::Center, default_column_width: 8))
       it "returns the Table itself" do
-        t23a.shrinkwrap!(max_table_width: [nil, 54, 47].sample).to_s.should eq(t23a.to_s)
+        t23a.shrinkwrap!(max_min_width: [0, 54, 47].sample).to_s.should eq(t23a.to_s)
       end
     end
 

src/table.cr

@@ -122,8 +122,9 @@ module Tablo
     # Note that calling this method will cause the entire source to
     # be traversed and all the column extractors and formatters to be applied in order
     # to calculate the required widths.
-    def shrinkwrap!(max_table_width = nil)
+    def shrinkwrap!(max_min_width = 0)
       return self if column_registry.none?
+
       columns = column_registry.values
 
       # Adjust column header width to its minimum by calling the `wrapped_with`
@@ -141,26 +142,111 @@ module Tablo
         end
       end
 
-      if max_table_width
+      # specific adjustments
+      if max_min_width != 0
         total_columns_width = columns.reduce(0) { |sum, column| sum + column.width }
         total_padding = column_registry.size * @column_padding * 2
         total_borders = column_registry.size + 1
         unadjusted_table_width = total_columns_width + total_padding + total_borders
 
         # Ensure max table width is at least wide enough to accommodate table borders and padding
         # and one character of content.
-        min_table_width = total_padding + total_borders + column_registry.size
-        max_table_width = min_table_width if min_table_width > max_table_width
+        if max_min_width < 0
+          # Minimum width required
+          min_table_width = [total_padding + total_borders + column_registry.size, max_min_width.abs].max
+          max_table_width = [unadjusted_table_width, min_table_width].max
+        else
+          # Maximum width required
+          min_table_width = total_padding + total_borders + column_registry.size
+          max_table_width = [unadjusted_table_width, max_min_width].min
+        end
 
-        required_reduction = [unadjusted_table_width - max_table_width, 0].max
+        # max_table_width = unadjusted_table_width if max_table_width == 0
+        # min_table_width = [total_padding + total_borders + column_registry.size, min_table_width].max
+        # max_table_width = [max_table_width, min_table_width].max
 
-        required_reduction.times do
-          widest_column = columns.reduce(columns.first) do |widest, column|
-            column.width >= widest.width ? column : widest
+        if unadjusted_table_width > max_table_width
+          required_adjustment = [unadjusted_table_width - max_table_width, 0].max
+          required_adjustment.times do
+            widest_column = columns.reduce(columns.first) do |widest, column|
+              column.width >= widest.width ? column : widest
+            end
+            widest_column.width -= 1
+          end
+        elsif unadjusted_table_width < min_table_width
+          required_adjustment = [min_table_width - unadjusted_table_width, 0].max
+          required_adjustment.times do
+            narrowest_column = columns.reduce(columns.first) do |narrowest, column|
+              column.width <= narrowest.width ? column : narrowest
+            end
+            narrowest_column.width += 1
           end
+        else
+          # nothoing to do
+        end
+
+        # required_reduction = [unadjusted_table_width - max_table_width, 0].max
+
+      end
+
+      self
+    end
+
+    def zzz_shrinkwrap!(max_table_width = 0, min_table_width = 0)
+      return self if column_registry.none?
+
+      columns = column_registry.values
+
+      # Adjust column header width to its minimum by calling the `wrapped_with`
+      # method
+      columns.each do |column|
+        column.width = wrapped_width(column.header)
+      end
 
-          widest_column.width -= 1
+      # Adjust column data width to its minimum by calling the `wrapped_with`
+      # on each source row
+      @sources.each do |source|
+        columns.each do |column|
+          width = wrapped_width(column.formatted_cell_content(source))
+          column.width = width if width > column.width
+        end
+      end
+
+      # specific adjustments
+      if max_table_width != 0 || min_table_width != 0
+        total_columns_width = columns.reduce(0) { |sum, column| sum + column.width }
+        total_padding = column_registry.size * @column_padding * 2
+        total_borders = column_registry.size + 1
+        unadjusted_table_width = total_columns_width + total_padding + total_borders
+
+        # Ensure max table width is at least wide enough to accommodate table borders and padding
+        # and one character of content.
+        max_table_width = unadjusted_table_width if max_table_width == 0
+        min_table_width = [total_padding + total_borders + column_registry.size, min_table_width].max
+        max_table_width = [max_table_width, min_table_width].max
+
+        if unadjusted_table_width > max_table_width
+          required_adjustment = [unadjusted_table_width - max_table_width, 0].max
+          required_adjustment.times do
+            widest_column = columns.reduce(columns.first) do |widest, column|
+              column.width >= widest.width ? column : widest
+            end
+            widest_column.width -= 1
+          end
+        elsif unadjusted_table_width < min_table_width
+          required_adjustment = [min_table_width - unadjusted_table_width, 0].max
+          required_adjustment.times do
+            narrowest_column = columns.reduce(columns.first) do |narrowest, column|
+              column.width <= narrowest.width ? column : narrowest
+            end
+            narrowest_column.width += 1
+          end
+        else
+          # nothoing to do
         end
+
+        # required_reduction = [unadjusted_table_width - max_table_width, 0].max
+
       end
 
       self

src/tablo.cr

@@ -2,6 +2,6 @@ require "./table.cr"
 require "./column.cr"
 
 module Tablo
-  VERSION = "0.9.2"
+  VERSION = "0.9.3"
   extend self
 end