1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157

//! `pad` handles padding and alignment within delimited strings
//!
//! While its primary use case is as a command line tool, this library
//! is provided in case a programmatic interface might be useful to someone.

use std::cmp::max;
use std::io;
use std::str::FromStr;

extern crate itertools;
use itertools::{Itertools, Position};

extern crate unicode_segmentation;
use unicode_segmentation::UnicodeSegmentation;


/// A Cell is a single field within a row
///
/// It is a string slice and the grapheme count within that string slice
pub type Cell<'input> = (&'input str, usize);

/// A Row is a list of Cells.
pub type Row<'input> = Vec<Cell<'input>>;

/// Split an input row into its component graphemes
///
/// This is more complex than it may appear at first glance, because we
/// properly handle Unicode grapheme clusters.
///
/// This function makes no attempt to split rows; that should be handled
/// externally.
pub fn split_row<'input>(input: &'input str, delimiter: char) -> Row<'input> {
    let mut row = Row::new();

    for substr in input.split(delimiter) {
        let graphemes = substr.graphemes(true).count();
        row.push((substr, graphemes));
    }

    row
}

pub type Document<'input> = Vec<Row<'input>>;

/// Parse an input string into a document
///
/// Note that this must retain references to the entire input string, which
/// effectively means that the entire input must remain in memory before output
/// can begin. This may cause problems for large inputs.
pub fn parse_document<'input>(input: &'input str, delimiter: char) -> Document<'input> {
    input.lines().map(|line| split_row(line, delimiter)).collect()
}

/// Alignment controls the alignment of the output within a column
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum Alignment {
    Left,
    Right,
    Center,
}

impl Default for Alignment {
    fn default() -> Alignment {
        Alignment::Left
    }
}

impl FromStr for Alignment {
    type Err = &'static str;
    fn from_str(input: &str) -> Result<Alignment, &'static str> {
        match input {
            "<" | "l" | "L" => Ok(Alignment::Left),
            "^" | "c" | "C" => Ok(Alignment::Center),
            ">" | "r" | "R" => Ok(Alignment::Right),
            _ => Err("invalid alignment character")
        }
    }
}

/// A Column is a basic unit of output
pub struct Column {
    alignment: Alignment,
    width: usize,
}

/// This struct configures the output of a document
pub struct OutputConfig {
    separator: char,
    columns: Vec<Column>,
}

/// Generate output configuration from the given document
pub fn configure_output(
    document: &Document,
    alignments: &[Alignment],
    output_separator: char,
) -> OutputConfig {
    let mut output = OutputConfig{
        separator: output_separator,
        columns: Vec::new(),
    };

    for row in document {
        for (idx, &(_, width)) in row.iter().enumerate() {
            if idx < output.columns.len() {
                // this column exists
                output.columns[idx].width = max(output.columns[idx].width, width);
            } else {
                output.columns.push(Column{
                    alignment: if idx < alignments.len() { alignments[idx] } else { Alignment::default() },
                    width: width,
                })
            }
        }
    }

    output
}

/// Write a column to the given writer
fn write_col<W: io::Write>(writer: &mut W, text: &str, width: usize, alignment: Alignment) -> io::Result<()> {
    match alignment {
        Alignment::Left => write!(writer, "{: <width$}", text, width=width)?,
        Alignment::Center => write!(writer, "{: ^width$}", text, width=width)?,
        Alignment::Right => write!(writer, "{: >width$}", text, width=width)?,
    }
    Ok(())
}

/// Write the given document to the specified writer using the given output configuration
pub fn write<'input, W: io::Write>(writer: &mut W, document: &Document<'input>, config: &OutputConfig, autoflush: bool) -> io::Result<()> {
    for row in document {
        for position in row.iter().zip(config.columns.iter()).with_position() {
            match position {
                Position::First((&(text, _), column)) | Position::Middle((&(text, _), column)) => {
                    write_col(writer, text, column.width, column.alignment)?;
                    write!(writer, "{}", config.separator)?;
                }

                Position::Last((&(text, _), column)) | Position::Only((&(text, _), column)) => {
                    write_col(writer, text, column.width, column.alignment)?;
                    writeln!(writer, "")?;
                }
            }
        }
        if autoflush {
            writer.flush()?;
        }
    }
    Ok(())
}

/// Print the given document to stdout using the given output configuration
pub fn print<'input>(document: &Document<'input>, config: &OutputConfig) -> io::Result<()> {
    let mut stdout = io::stdout();
    write(&mut stdout, document, config, true)
}