Pretty Markdown tables (#5)

* Pretty Markdown tables

* Update README

* Improve coverage

README.md

@@ -73,20 +73,21 @@ print(table.markdown)
 
 Generates the following output:
 
-    |   | Name | Department |
-    | - | ---- | ---------- |
-    | 🍏 | Apple | Fruits |
-    | 🍊 | Orange | Fruits |
-    | 🥖 | Bread | Bakery |
+    |    | Name   | Department |
+    | -- | ------ | ---------- |
+    | 🍏 | Apple  | Fruits     |
+    | 🍊 | Orange | Fruits     |
+    | 🥖 | Bread  | Bakery     |
 
 Which renders as:
 
-|   | Name | Department |
-| - | ---- | ---------- |
-| 🍏 | Apple | Fruits |
-| 🍊 | Orange | Fruits |
-| 🥖 | Bread | Bakery |
+|    | Name   | Department |
+| -- | ------ | ---------- |
+| 🍏 | Apple  | Fruits     |
+| 🍊 | Orange | Fruits     |
+| 🥖 | Bread  | Bakery     |
 
+Pretty tables 🎉
 
 ### Blockquotes
 
@@ -162,8 +163,8 @@ Generates the following output:
 
     | Name | Count |
     | ---- | ----- |
-    | Dog | 1 |
-    | Cat | 2 |
+    | Dog  | 1     |
+    | Cat  | 2     |
 
     ```swift
     let foo = Bar()
@@ -182,8 +183,8 @@ Which renders as (click to expand):
 
 | Name | Count |
 | ---- | ----- |
-| Dog | 1 |
-| Cat | 2 |
+| Dog  | 1     |
+| Cat  | 2     |
 
 ```swift
 let foo = Bar()

Sources/MarkdownGenerator/MarkdownTable.swift

@@ -9,11 +9,11 @@ import Foundation
 
 /// Render a two dimensional Markdown table.
 ///
-///     |   | Name | Department |
-///     | - | ---- | ---------- |
-///     | 🍏 | Apple | Fruits |
-///     | 🍊 | Orange | Fruits |
-///     | 🥖 | Bread | Bakery |
+///     |    | Name   | Department |
+///     | -- | ------ | ---------- |
+///     | 🍏 | Apple  | Fruits     |
+///     | 🍊 | Orange | Fruits     |
+///     | 🥖 | Bread  | Bakery     |
 ///
 /// *Notes*:
 /// - Markdown tables are not supported by all Markdown readers.
@@ -40,10 +40,14 @@ public struct MarkdownTable: MarkdownConvertible {
 
     /// Generated Markdown output
     public var markdown: String {
-        let headerRow = makeRow(values: headers)
-        let separatorRow = makeRow(values: headers.map { Array(repeating: "-", count: $0.count).joined() })
+        let columnWidths = computeColumnWidths()
+        if columnWidths.isEmpty {
+            return .newLine
+        }
+        let headerRow = makeRow(values: pad(values: headers, lengths: columnWidths))
+        let separatorRow = makeRow(values: columnWidths.map { String(repeating: "-", count: $0) })
         let dataRows = data.map { columns in
-            return makeRow(values: columns)
+            return makeRow(values: pad(values: columns, lengths: columnWidths))
         }
         return """
         \(headerRow)
@@ -52,10 +56,56 @@ public struct MarkdownTable: MarkdownConvertible {
         """
     }
 
-    // Convert a String array into a markdown formatter table row.
-    // Table cells cannot contain multiple lines. New line characters are replaced by a space.
-    private func makeRow(values: [String]) -> String {
+    /// Return max length for each column, counting individual UTF16 characters for better emoji support.
+    ///
+    /// - Returns: Array of column widths
+    func computeColumnWidths() -> [Int] {
+        let rows = [headers] + data
+        guard let maxColumns = rows.map({ $0.count }).max(), maxColumns > 0 else {
+            return []
+        }
+        let columnWidths = (0..<maxColumns).map { columnIndex -> Int in
+            return columnLength(values: rows.compactMap({ $0.get(at: columnIndex) }))
+        }
+        return columnWidths
+    }
+
+    func columnLength(values: [String]) -> Int {
+        return values.map({ $0.utf16.count }).max() ?? 0
+    }
+
+    /// Pad array of strings to a given length, counting individual UTF16 characters
+    ///
+    /// - Parameters:
+    ///   - values: array of strings to pad
+    ///   - lengths: desired lengths
+    /// - Returns: array of right-padded strings
+    func pad(values: [String], lengths: [Int]) -> [String] {
+        var values = values
+        while values.count < lengths.count {
+            values.append("")
+        }
+        return zip(values, lengths).map { value, length in
+            value + String(repeating: " ", count: max(0, length - value.utf16.count))
+        }
+    }
+
+    /// Convert a String array into a markdown formatter table row.
+    /// Table cells cannot contain multiple lines. New line characters are replaced by a space.
+    ///
+    /// - Parameter values: array of values
+    /// - Returns: Markdown formatted row
+    func makeRow(values: [String]) -> String {
         let values = values.map { $0.replacingOccurrences(of: String.newLine, with: " ") }
         return "| " + values.joined(separator: " | ") + " |"
     }
 }
+
+extension Array {
+    func get(at index: Int) -> Element? {
+        guard (0..<count).contains(index) else {
+            return nil
+        }
+        return self[index]
+    }
+}

Tests/MarkdownGeneratorTests/Internal/MarkdownTableInternalTests.swift

@@ -0,0 +1,22 @@
+//
+//  MarkdownTableTests.swift
+//  MarkdownGeneratorTests
+//
+//  Created by Eneko Alonso on 11/28/18.
+//
+
+import XCTest
+@testable import MarkdownGenerator
+
+class MarkdownTableInternalTests: XCTestCase {
+
+    func testEmptyColumnLength() {
+        let table = MarkdownTable(headers: [], data: [])
+        XCTAssertEqual(table.columnLength(values: []), 0)
+    }
+
+    func testEmptyColumnWidths() {
+        let table = MarkdownTable(headers: [], data: [])
+        XCTAssertEqual(table.computeColumnWidths(), [])
+    }
+}

Tests/MarkdownGeneratorTests/MarkdownCollapsibleSectionTests.swift → Tests/MarkdownGeneratorTests/PublicInterface/MarkdownCollapsibleSectionTests.swift

@@ -33,8 +33,8 @@ class MarkdownCollapsibleSectionTests: XCTestCase {
 
         | Name | Count |
         | ---- | ----- |
-        | Dog | 1 |
-        | Cat | 2 |
+        | Dog  | 1     |
+        | Cat  | 2     |
 
         ```swift
         let foo = Bar()

Tests/MarkdownGeneratorTests/MarkdownTableTests.swift → Tests/MarkdownGeneratorTests/PublicInterface/MarkdownTableTests.swift

@@ -10,14 +10,19 @@ import MarkdownGenerator
 
 class MarkdownTableTests: XCTestCase {
 
+    func testEmptyTable() {
+        let table = MarkdownTable(headers: [], data: [])
+        XCTAssertEqual(table.markdown, "\n")
+    }
+
     func test1x1Table() {
         let data: [[String]] = [[]]
         let table = MarkdownTable(headers: ["Header"], data: data)
 
         let output = """
         | Header |
         | ------ |
-        |  |
+        |        |
         """
 
         XCTAssertEqual(table.markdown, output)
@@ -32,11 +37,11 @@ class MarkdownTableTests: XCTestCase {
         let table = MarkdownTable(headers: ["", "Name", "Department"], data: data)
 
         let output = """
-        |   | Name | Department |
-        | - | ---- | ---------- |
-        | 🍏 | Apple | Fruits |
-        | 🍊 | Orange | Fruits |
-        | 🥖 | Bread | Bakery |
+        |    | Name   | Department |
+        | -- | ------ | ---------- |
+        | 🍏 | Apple  | Fruits     |
+        | 🍊 | Orange | Fruits     |
+        | 🥖 | Bread  | Bakery     |
         """
 
         XCTAssertEqual(table.markdown, output)
@@ -51,8 +56,8 @@ class MarkdownTableTests: XCTestCase {
         let table = MarkdownTable(headers: ["Single-line", "Multi-line"], data: data)
 
         let output = """
-        | Single-line | Multi-line |
-        | ----------- | ---------- |
+        | Single-line       | Multi-line        |
+        | ----------------- | ----------------- |
         | Single-line value | Multi-line  value |
         | Single-line value | Multi-line  value |
         | Single-line value | Multi-line  value |
@@ -61,6 +66,20 @@ class MarkdownTableTests: XCTestCase {
         XCTAssertEqual(table.markdown, output)
     }
 
+    func testMixedTable() {
+        let table = MarkdownTable(headers: ["Foo"], data: [["Bar"], [], ["Baz", "Bax"]])
+
+        let output = """
+        | Foo |     |
+        | --- | --- |
+        | Bar |     |
+        |     |     |
+        | Baz | Bax |
+        """
+
+        XCTAssertEqual(table.markdown, output)
+    }
+
     static var allTests = [
         ("test1x1Table", test1x1Table),
         ("test3x3Table", test3x3Table),