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

use crate::runtime::op::{Operation, ScopePersister, SigStatement};
use crate::runtime::{Environment, Event, Scope};
use crate::{ast, lex, lint};

use regex::Regex;
use std::fs::File;
use std::io::{BufRead, Read, Write};

/// The interpreter which processes lines with a romulus program
pub struct Interpreter {
    node: ast::Seq,
    sep: Regex,
    implicit_print: bool,
}

/// Builds an interpreter
pub struct Builder {
    filename: Option<String>,
    expression: Option<String>,
    sep: Option<Regex>,
    print: Option<bool>,
}

impl Interpreter {
    /// Process an input stream and writes the results for it's romulus program to
    /// the output stream
    pub fn process<R: BufRead, W: Write>(&self, sin: &mut R, sout: &mut W) {
        let mut iter = sin.lines();
        let mut env = Environment::new(sout, &self.node, self.sep.clone());

        if cfg!(feature = "envvar") {
            env.push(Scope::env());
        }

        let implicit_print = !self.node.significant();

        env.event = Event::Begin;
        self.node.perform(&mut env);

        while let Some(Ok(line)) = iter.next() {
            env.lineno += 1;
            env.event = Event::Line(line);

            self.node.persist_scope(&mut env);
            self.node.perform(&mut env);

            if env.finished() {
                return;
            }

            if implicit_print && self.implicit_print {
                env.print_event();
            }
        }

        env.event = Event::End;
        self.node.perform(&mut env);
    }

    /// Lint the current program
    pub fn lint(&self) -> Vec<lint::LintMessage> {
        lint::lint(&self.node)
    }

    /// Create a new interpreter builder
    pub fn builder() -> Builder {
        Builder {
            filename: None,
            expression: None,
            sep: None,
            print: None,
        }
    }
}

impl Builder {
    /// Sets a filename to be read
    pub fn filename(&mut self, filename: String) -> &mut Self {
        self.filename = Some(filename);
        self
    }

    /// Sets an expression
    pub fn expression(&mut self, expression: String) -> &mut Self {
        self.expression = Some(expression);
        self
    }

    /// sets the seperator
    pub fn sep(&mut self, sep: Regex) -> &mut Self {
        self.sep = Some(sep);
        self
    }

    /// sets the implicit printing
    pub fn print(&mut self, print: bool) -> &mut Self {
        self.print = Some(print);
        self
    }

    /// Builds the interpreter
    pub fn build(&mut self) -> Result<Interpreter, String> {
        let node = match (&self.filename, &self.expression) {
            (None, None) => return Err(String::from("Neither an expression or a file was given")),
            (Some(_), Some(_)) => {
                return Err(String::from(
                    "Both expression and file should not be given at the same time",
                ))
            }

            (Some(ref file), None) => {
                let mut file = match File::open(file) {
                    Ok(f) => f,
                    Err(err) => {
                        return Err(format!(
                            "unable to open file romulus file '{}': {}",
                            file, err
                        ))
                    }
                };

                let mut buf = String::new();
                if let Err(err) = file.read_to_string(&mut buf) {
                    return Err(format!("unable to read romulus file: {}", err));
                }

                let tokens = lex::lex(buf.as_ref())?;
                ast::parse(tokens)?
            }
            (None, Some(expr)) => {
                let tokens = lex::lex(expr.as_ref())?;
                ast::parse(tokens)?
            }
        };

        let sep = self
            .sep
            .clone()
            .unwrap_or_else(|| Regex::new(" +").unwrap());

        let implicit_print = self.print.unwrap_or(true);

        Ok(Interpreter {
            node,
            sep,
            implicit_print,
        })
    }
}