Add TextTable class for table output

Signed-off-by: Dan Mick <dan.mick@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

1 files changed, 159 insertions, 0 deletions

diff --git a/src/common/TextTable.h b/src/common/TextTable.h
new file mode 100644
index 00000000000..44d0aa4cd46
--- /dev/null
+++ b/src/common/TextTable.h
@@ -0,0 +1,159 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2012 Inktank Storage, Inc.
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+#include <vector>
+#include <sstream>
+#include <iomanip>
+#include <string>
+#include "include/assert.h"
+
+/**
+ * TextTable:
+ * Manage tabular output of data.  Caller defines heading of each column
+ * and alignment of heading and column data,
+ * then inserts rows of data including tuples of
+ * length (ncolumns) terminated by TextTable::endrow.  When all rows
+ * are inserted, caller asks for output with ostream <<
+ * which sizes/pads/dumps the table to ostream.
+ *
+ * Columns autosize to largest heading or datum.  One space is printed
+ * between columns.
+ */
+
+class TextTable {
+
+public:
+  enum Align {LEFT = 1, CENTER, RIGHT};
+
+private:
+  struct TextTableColumn {
+    std::string heading;
+    int width;
+    Align hd_align;
+    Align col_align;
+
+    TextTableColumn() {};
+    TextTableColumn(std::string h, int w, Align ha, Align ca) :
+		    heading(h), width(w), hd_align(ha), col_align(ca) { }
+    ~TextTableColumn() {}
+  };
+
+  std::vector<TextTableColumn> col;	// column definitions
+  std::vector<std::vector<std::string> > row;	// row data array
+  unsigned int curcol, currow;		// col, row being inserted into
+  unsigned int indent;			// indent width when rendering
+
+public:
+  TextTable(): curcol(0), currow(0), indent(0) {}
+  ~TextTable() {}
+
+  /**
+   * Define a column in the table.
+   *
+   * @param heading Column heading string (or "")
+   * @param hd_align Alignment for heading in column
+   * @param col_align Data alignment
+   *
+   * @note alignment is of type TextTable::Align; values are
+   * TextTable::LEFT, TextTable::CENTER, or TextTable::RIGHT
+   *
+   */
+  void define_column(const std::string heading, Align hd_align,
+		     Align col_align);
+
+  /**
+   * Set indent for table.  Only affects table output.
+   *
+   * @param i Number of spaces to indent
+   */
+  void set_indent(int i) { indent = i; }
+
+  /**
+   * Add item to table, perhaps on new row.
+   * table << val1 << val2 << TextTable::endrow;
+   *
+   * @param: value to output.
+   *
+   * @note: Numerics are output in decimal; strings are not truncated.
+   * Output formatting choice is limited to alignment in define_column().
+   *
+   * @return TextTable& for chaining.
+   */
+
+  template<typename T> TextTable& operator<<(const T& item)
+  {
+    if (row.size() < currow + 1)
+      row.resize(currow + 1);
+
+    /**
+     * col.size() is a good guess for how big row[currow] needs to be,
+     * so just expand it out now
+     */
+    if (row[currow].size() < col.size()) {
+      row[currow].resize(col.size());
+    }
+
+    // inserting more items than defined columns is a coding error
+    assert(curcol + 1 <= col.size());
+
+    // get rendered width of item alone
+    std::ostringstream oss;
+    oss << item;
+    int width = oss.str().length();
+    oss.seekp(0);
+
+    // expand column width if necessary
+    if (width > col[curcol].width) {
+      col[curcol].width = width;
+    }
+
+    // now store the rendered item with its proper width
+    oss << std::setw(width) << item;
+    row[currow][curcol] = oss.str();
+
+    curcol++;
+    return *this;
+  }
+
+  /**
+   * Degenerate type/variable here is just to allow selection of the
+   * following operator<< for "<< TextTable::endrow"
+   */
+
+  struct endrow_t {};
+  static endrow_t endrow;
+
+  /**
+   * Implements TextTable::endrow
+   */
+
+  TextTable &operator<<(endrow_t)
+  {
+    curcol = 0;
+    currow++;
+    return *this;
+  }
+
+  /**
+   * Render table to ostream (i.e. cout << table)
+   */
+
+  friend std::ostream &operator<<(std::ostream& out, TextTable &t);
+
+  /**
+   * clear: Reset everything in a TextTable except column defs
+   * resize cols to heading widths, clear indent
+   */
+
+  void clear();
+};