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/*
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 * Hurl (https://hurl.dev)
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 * Copyright (C) 2024 Orange
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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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 *
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 */
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use crate::ast::{Placeholder, SourceInfo, TemplateElement};
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use crate::parser::primitives::zero_or_more_spaces;
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use crate::parser::{error, expr, ParseResult};
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use crate::reader::{Pos, Reader};
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pub struct EncodedString {
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    pub source_info: SourceInfo,
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    pub chars: Vec<(char, String, Pos)>,
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}
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pub fn templatize(encoded_string: EncodedString) -> ParseResult<Vec<TemplateElement>> {
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    enum State {
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        String,
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        Template,
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        FirstOpenBracket,
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        FirstCloseBracket,
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    }
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    let mut elements = vec![];
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    let mut value = String::new();
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    let mut encoded = String::new();
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    let mut state = State::String;
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    let mut expression_start = None;
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    for (c, s, pos) in encoded_string.chars {
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        match state {
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            State::String => {
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                if s.as_str() == "{" {
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                    state = State::FirstOpenBracket;
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                } else {
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                    value.push(c);
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                    encoded.push_str(&s.clone());
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                }
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            }
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            State::FirstOpenBracket => {
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                if s.as_str() == "{" {
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                    if !value.is_empty() {
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                        elements.push(TemplateElement::String { value, encoded });
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                        value = String::new();
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                        encoded = String::new();
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                    }
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                    state = State::Template;
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                } else {
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                    value.push('{');
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                    encoded.push('{');
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                    value.push(c);
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                    encoded.push_str(&s.clone());
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                    state = State::String;
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                }
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            }
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            State::Template => {
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                if expression_start.is_none() {
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                    expression_start = Some(pos);
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                }
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                if s.as_str() == "}" {
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                    state = State::FirstCloseBracket;
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                } else {
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                    value.push(c);
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                    encoded.push_str(&s.clone());
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                }
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            }
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            State::FirstCloseBracket => {
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                if s.as_str() == "}" {
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                    let mut reader = Reader::with_pos(encoded.as_str(), expression_start.unwrap());
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                    let space0 = zero_or_more_spaces(&mut reader)?;
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                    let expr = expr::parse(&mut reader)?;
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                    let space1 = zero_or_more_spaces(&mut reader)?;
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                    let placeholder = Placeholder {
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                        space0,
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                        expr,
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                        space1,
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                    };
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                    elements.push(TemplateElement::Placeholder(placeholder));
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                    value = String::new();
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                    encoded = String::new();
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                    expression_start = None;
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                    state = State::String;
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                } else {
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                    value.push('}');
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                    value.push(c);
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                    encoded.push('}');
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                    encoded.push_str(&s.clone());
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                }
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            }
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        }
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    }
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    match state {
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        State::String => {}
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        State::FirstOpenBracket => {
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            value.push('{');
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            encoded.push('{');
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        }
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        State::Template | State::FirstCloseBracket => {
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            let kind = error::ParseErrorKind::Expecting {
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                value: "}}".to_string(),
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            };
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            return Err(error::ParseError::new(
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                encoded_string.source_info.end,
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                false,
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                kind,
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            ));
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        }
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    }
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    if !value.is_empty() {
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        elements.push(TemplateElement::String { value, encoded });
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    }
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    Ok(elements)
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}
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#[cfg(test)]
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mod tests {
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    use super::*;
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    use crate::ast::{Expr, ExprKind, Placeholder, Variable, Whitespace};
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    #[test]
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    fn test_templatize_empty_string() {
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        let encoded_string = EncodedString {
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            source_info: SourceInfo::new(Pos::new(1, 1), Pos::new(1, 1)),
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            chars: vec![],
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        };
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        assert_eq!(templatize(encoded_string).unwrap(), vec![]);
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    }
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    #[test]
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    fn test_templatize_hello_world() {
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        // Hi\u0020{{name}}!
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        let encoded_string = EncodedString {
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            source_info: SourceInfo::new(Pos::new(1, 1), Pos::new(1, 18)),
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            chars: vec![
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                ('H', "H".to_string(), Pos { line: 1, column: 1 }),
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                ('i', "i".to_string(), Pos { line: 1, column: 2 }),
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                (' ', "\\u0020".to_string(), Pos { line: 1, column: 3 }),
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                ('{', "{".to_string(), Pos { line: 1, column: 9 }),
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                (
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                    '{',
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                    "{".to_string(),
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                    Pos {
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                        line: 1,
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                        column: 10,
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                    },
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                ),
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                (
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                    'n',
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                    "n".to_string(),
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                    Pos {
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                        line: 1,
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                        column: 11,
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                    },
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                ),
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                (
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                    'a',
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                    "a".to_string(),
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                    Pos {
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                        line: 1,
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                        column: 12,
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                    },
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                ),
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                (
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                    'm',
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                    "m".to_string(),
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                    Pos {
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                        line: 1,
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                        column: 13,
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                    },
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                ),
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                (
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                    'e',
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                    "e".to_string(),
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                    Pos {
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                        line: 1,
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                        column: 14,
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                    },
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                ),
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                (
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                    '}',
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                    "}".to_string(),
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                    Pos {
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                        line: 1,
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                        column: 15,
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                    },
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                ),
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                (
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                    '}',
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                    "}".to_string(),
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                    Pos {
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                        line: 1,
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                        column: 16,
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                    },
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                ),
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                (
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                    '!',
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                    "!".to_string(),
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                    Pos {
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                        line: 1,
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                        column: 17,
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                    },
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                ),
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            ],
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        };
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        assert_eq!(
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            templatize(encoded_string).unwrap(),
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            vec![
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                TemplateElement::String {
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                    value: "Hi ".to_string(),
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                    encoded: "Hi\\u0020".to_string(),
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                },
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                TemplateElement::Placeholder(Placeholder {
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                    space0: Whitespace {
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                        value: String::new(),
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                        source_info: SourceInfo::new(Pos::new(1, 11), Pos::new(1, 11)),
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                    },
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                    expr: Expr {
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                        kind: ExprKind::Variable(Variable {
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                            name: "name".to_string(),
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                            source_info: SourceInfo::new(Pos::new(1, 11), Pos::new(1, 15)),
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                        }),
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                        source_info: SourceInfo::new(Pos::new(1, 11), Pos::new(1, 15)),
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                    },
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                    space1: Whitespace {
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                        value: String::new(),
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                        source_info: SourceInfo::new(Pos::new(1, 15), Pos::new(1, 15)),
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                    },
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                }),
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                TemplateElement::String {
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                    value: "!".to_string(),
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                    encoded: "!".to_string(),
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                },
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            ]
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        );
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    }
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    #[test]
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    fn test_templatize_expression_only() {
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        // {{x}}!
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        let encoded_string = EncodedString {
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            source_info: SourceInfo::new(Pos::new(1, 1), Pos::new(1, 7)),
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            chars: vec![
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                ('{', "{".to_string(), Pos { line: 1, column: 1 }),
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                ('{', "{".to_string(), Pos { line: 1, column: 2 }),
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                ('x', "x".to_string(), Pos { line: 1, column: 3 }),
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                ('}', "}".to_string(), Pos { line: 1, column: 4 }),
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                ('}', "}".to_string(), Pos { line: 1, column: 4 }),
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            ],
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        };
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        assert_eq!(
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            templatize(encoded_string).unwrap(),
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            vec![TemplateElement::Placeholder(Placeholder {
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                space0: Whitespace {
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                    value: String::new(),
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                    source_info: SourceInfo::new(Pos::new(1, 3), Pos::new(1, 3)),
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                },
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                expr: Expr {
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                    kind: ExprKind::Variable(Variable {
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                        name: "x".to_string(),
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                        source_info: SourceInfo::new(Pos::new(1, 3), Pos::new(1, 4)),
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                    }),
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                    source_info: SourceInfo::new(Pos::new(1, 3), Pos::new(1, 4))
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                },
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                space1: Whitespace {
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                    value: String::new(),
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                    source_info: SourceInfo::new(Pos::new(1, 4), Pos::new(1, 4)),
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                },
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            }),]
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        );
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    }
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    #[test]
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    fn test_templatize_error() {
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        // missing closing
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        // {{x
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        let encoded_string = EncodedString {
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            source_info: SourceInfo::new(Pos::new(1, 1), Pos::new(1, 4)),
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            chars: vec![
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                ('{', "{".to_string(), Pos { line: 1, column: 1 }),
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                ('{', "{".to_string(), Pos { line: 1, column: 2 }),
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                ('x', "x".to_string(), Pos { line: 1, column: 3 }),
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            ],
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        };
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        let error = templatize(encoded_string).err().unwrap();
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        assert_eq!(error.pos, Pos { line: 1, column: 4 });
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        assert_eq!(
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            error.kind,
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            error::ParseErrorKind::Expecting {
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                value: "}}".to_string()
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            }
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        );
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        assert!(!error.recoverable);
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    }
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    #[test]
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    fn test_escape_bracket() {
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        // \{\{
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        // This is a valid string "{{"
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        let encoded_string = EncodedString {
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            source_info: SourceInfo::new(Pos::new(1, 1), Pos::new(1, 4)),
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            chars: vec![
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                ('{', "\\{".to_string(), Pos { line: 1, column: 1 }),
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                ('{', "\\{".to_string(), Pos { line: 1, column: 2 }),
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            ],
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        };
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        assert_eq!(
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            templatize(encoded_string).unwrap(),
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            vec![TemplateElement::String {
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                value: "{{".to_string(),
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                encoded: "\\{\\{".to_string(),
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            },]
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        );
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    }
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}