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103 lines
3.4 KiB
Rust
103 lines
3.4 KiB
Rust
// Copyright 2017 Jeremy Wall <jeremy@marzhillstudios.com>
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//! The format string logic for ucg format expressions.
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use std::clone::Clone;
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use std::error::Error;
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use ast::*;
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use error;
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/// Implements the logic for format strings in UCG format expressions.
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pub struct Formatter<V: Into<String> + Clone> {
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tmpl: String,
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args: Vec<V>,
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}
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impl<V: Into<String> + Clone> Formatter<V> {
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/// Constructs a Formatter with a template and args.
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pub fn new<S: Into<String>>(tmpl: S, args: Vec<V>) -> Self {
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Formatter {
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tmpl: tmpl.into(),
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args: args,
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}
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}
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/// Renders a formatter to a string or returns an error.
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///
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/// If the formatter has the wrong number of arguments for the number of replacements
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/// it will return an error. Otherwise it will return the formatted string.
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pub fn render(&self, pos: &Position) -> Result<String, Box<Error>> {
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let mut buf = String::new();
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let mut should_escape = false;
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let mut count = 0;
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for c in self.tmpl.chars() {
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if c == '@' && !should_escape {
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if count == self.args.len() {
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return Err(Box::new(error::Error::new(
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"Too few arguments to string \
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formatter.",
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error::ErrorType::FormatError,
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pos.clone(),
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)));
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}
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let arg = self.args[count].clone();
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let strval = arg.into();
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buf.push_str(&strval);
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count += 1;
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} else if c == '\\' && !should_escape {
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should_escape = true;
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} else {
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buf.push(c);
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}
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}
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if self.args.len() != count {
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return Err(Box::new(error::Error::new(
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"Too many arguments to string \
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formatter.",
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error::ErrorType::FormatError,
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pos.clone(),
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)));
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}
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return Ok(buf);
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}
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}
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#[cfg(test)]
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mod test {
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use super::Formatter;
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use ast::Position;
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#[test]
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fn test_format_happy_path() {
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let formatter = Formatter::new("foo @ @ \\@", vec!["bar", "quux"]);
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let pos = Position { line: 0, column: 0 };
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assert_eq!(formatter.render(&pos).unwrap(), "foo bar quux @");
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}
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#[test]
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fn test_format_happy_wrong_too_few_args() {
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let formatter = Formatter::new("foo @ @ \\@", vec!["bar"]);
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let pos = Position { line: 0, column: 0 };
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assert!(formatter.render(&pos).is_err());
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}
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#[test]
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fn test_format_happy_wrong_too_many_args() {
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let formatter = Formatter::new("foo @ @ \\@", vec!["bar", "quux", "baz"]);
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let pos = Position { line: 0, column: 0 };
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assert!(formatter.render(&pos).is_err());
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}
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}
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