Format the reader module
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parent
5181c84696
commit
25c58c27c2
157
src/reader.rs
157
src/reader.rs
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@ -1,44 +1,42 @@
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use crate::ast::{Expr, Number};
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use std::io::{Read, BufReader};
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use std::io::{BufReader, Read};
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pub type ReadResult = Result<Expr, String>;
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pub struct ExprReader {
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read_stack: Vec<char>
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read_stack: Vec<char>,
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}
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impl ExprReader {
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fn new() -> ExprReader {
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ExprReader {
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read_stack: vec![]
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}
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ExprReader { read_stack: vec![] }
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}
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fn get_char<T: Read>(&mut self, reader: &mut BufReader<T>, skip_whitespace: bool) -> Option<char> {
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fn get_char<T: Read>(
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&mut self,
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reader: &mut BufReader<T>,
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skip_whitespace: bool,
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) -> Option<char> {
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loop {
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match self.read_stack.pop() {
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Some(c) if !c.is_whitespace() || !skip_whitespace =>
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{
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return Some(c)
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},
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Some(c) if !c.is_whitespace() || !skip_whitespace => return Some(c),
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Some(_) => continue,
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None => ()
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None => (),
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};
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// Rust is weird, it doesn't provide a way to read from a buffer char by char.
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let mut single_char_buff = [0];
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let bytes_read = reader.read(&mut single_char_buff);
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match bytes_read {
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Ok(n) if n > 0 => {},
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Ok(n) if n > 0 => {}
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Ok(_) => return None,
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Err(_) => return None
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Err(_) => return None,
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};
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let ch = single_char_buff[0] as char;
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match ch {
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c if !c.is_whitespace() || !skip_whitespace => return Some(c),
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_ => (),
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_ => (),
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};
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}
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}
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@ -49,19 +47,26 @@ impl ExprReader {
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// Look ahead. AFAIK Rust doesn't provide any unread functoinality like Java input streams which
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// sucks.
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fn peek_char<T: Read>(&mut self, reader: &mut BufReader<T>, skip_whitespace: bool) -> Option<char> {
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fn peek_char<T: Read>(
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&mut self,
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reader: &mut BufReader<T>,
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skip_whitespace: bool,
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) -> Option<char> {
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match self.get_char(reader, skip_whitespace) {
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Some(c) => {
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self.unget_char(c);
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Some(c)
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},
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None => None
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}
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None => None,
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}
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}
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fn read_quoted_expr<T: Read>(&mut self, reader: &mut BufReader<T>) -> ReadResult {
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let rest = self.read_expr(reader)?;
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Ok(Expr::Cons(Box::new(Expr::Symbol("quote".to_string())), Box::new(rest)))
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Ok(Expr::Cons(
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Box::new(Expr::Symbol("quote".to_string())),
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Box::new(rest),
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))
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}
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fn read_unquoted_expr<T: Read>(&mut self, reader: &mut BufReader<T>) -> ReadResult {
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@ -70,21 +75,27 @@ impl ExprReader {
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// Move forward in the buffer since we peeked it
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let _ = self.get_char(reader, true);
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let rest = self.read_expr(reader)?;
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Ok(Expr::Cons(Box::new(Expr::Symbol("unquote-splicing".to_string())),
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Box::new(rest)))
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},
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Ok(Expr::Cons(
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Box::new(Expr::Symbol("unquote-splicing".to_string())),
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Box::new(rest),
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))
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}
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_ => {
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let rest = self.read_expr(reader)?;
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Ok(Expr::Cons(Box::new(Expr::Symbol("unquote".to_string())),
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Box::new(rest)))
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Ok(Expr::Cons(
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Box::new(Expr::Symbol("unquote".to_string())),
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Box::new(rest),
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))
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}
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}
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}
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fn read_quasiquoted_expr<T: Read>(&mut self, reader: &mut BufReader<T>) -> ReadResult {
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let rest = self.read_expr(reader)?;
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Ok(Expr::Cons(Box::new(Expr::Symbol("quasiquote".to_string())),
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Box::new(rest)))
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Ok(Expr::Cons(
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Box::new(Expr::Symbol("quasiquote".to_string())),
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Box::new(rest),
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))
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}
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// TODO: We might want to replace Cons with an actual List struct
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@ -95,15 +106,15 @@ impl ExprReader {
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// is it an empty list ?
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// TODO: we might want to return an actual empty list here
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Some(')') => return Ok(Expr::Nil),
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_ => return Err(e)
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}
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_ => return Err(e),
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},
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};
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let rest = match self.get_char(reader, true) {
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Some(e) => {
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self.unget_char(e);
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self.read_list(reader)?
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},
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None => return Err("Unexpected EOF, expected . or symbol".to_string())
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}
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None => return Err("Unexpected EOF, expected . or symbol".to_string()),
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};
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Ok(Expr::Cons(Box::new(first), Box::new(rest)))
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@ -111,10 +122,28 @@ impl ExprReader {
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fn is_valid_for_identifier(&self, c: char) -> bool {
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match c {
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'!' | '$' | '%' | '&' | '*' | '+' | '-' | '.' | '~' |
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'/' | ':' | '<' | '=' | '>' | '?' | '@' | '^' | '_' |
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'a'..='z' | 'A'..='Z' | '0'..='9' => true,
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_ => false
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'!'
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| '$'
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| '%'
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| '&'
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| '*'
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| '+'
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| '-'
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| '.'
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| '~'
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| '/'
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| ':'
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| '<'
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| '='
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| '>'
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| '?'
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| '@'
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| '^'
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| '_'
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| 'a'..='z'
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| 'A'..='Z'
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| '0'..='9' => true,
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_ => false,
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}
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}
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@ -126,11 +155,14 @@ impl ExprReader {
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let mut s = String::new();
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s.push(ch);
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s
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},
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}
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Some(e) => {
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return Err(format!("Unexpected character: got {}, expected a symbol", e))
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},
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None => return Err("Unexpected EOF".to_string())
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return Err(format!(
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"Unexpected character: got {}, expected a symbol",
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e
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))
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}
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None => return Err("Unexpected EOF".to_string()),
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};
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loop {
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@ -139,8 +171,8 @@ impl ExprReader {
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Some(v) => {
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self.unget_char(v);
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break;
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},
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None => break
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}
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None => break,
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}
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}
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@ -156,9 +188,9 @@ impl ExprReader {
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'n' => Some('\n'),
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'r' => Some('\r'),
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't' => Some('\t'),
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_ => None
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_ => None,
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},
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None => None
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None => None,
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}
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}
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@ -173,29 +205,26 @@ impl ExprReader {
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'\"' => break,
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'\\' => match self.read_escape_char(reader) {
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Some(v) => string.push(v),
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None => return Err(format!("Unexpected char to escape, got {}", e))
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None => return Err(format!("Unexpected char to escape, got {}", e)),
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},
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//'\n' => return Err("Unescaped newlines are not allowed in string literals".to_string()),
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_ => string.push(e)
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_ => string.push(e),
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},
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None => return Err("Unexpected EOF while scanning a string".to_string())
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None => return Err("Unexpected EOF while scanning a string".to_string()),
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}
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}
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Ok(Expr::Str(string))
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}
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fn read_number<T: Read>(&mut self, reader: &mut BufReader<T>, neg: bool) -> ReadResult {
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let mut is_double = false;
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let mut string = (if neg {
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"-"
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} else {
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""
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}).to_string();
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let mut string = (if neg { "-" } else { "" }).to_string();
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loop {
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match self.get_char(reader, false) {
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Some(e) if e == '.' && is_double => return Err("A double with more that one '.' ???".to_string()),
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Some(e) if e == '.' && is_double => {
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return Err("A double with more that one '.' ???".to_string())
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}
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Some(e) if e == '.' => {
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is_double = true;
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string.push(e);
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@ -205,7 +234,7 @@ impl ExprReader {
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self.unget_char(e);
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break;
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}
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None => break
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None => break,
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}
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}
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if is_double {
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@ -239,11 +268,10 @@ impl ExprReader {
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}
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}
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}
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// Neg number
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// }
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_ => self._read_symbol(reader)
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_ => self._read_symbol(reader),
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},
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None => Err("Unexpected EOF while scanning atom".to_string())
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None => Err("Unexpected EOF while scanning atom".to_string()),
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}
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}
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@ -257,23 +285,26 @@ impl ExprReader {
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'(' => self.read_list(reader),
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//'[' => self.read_vector(reader),
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//'{' => self.read_map(reader),
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_ => {
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_ => {
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self.unget_char(c);
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self.read_symbol(reader)
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}
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}
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},
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None => Ok(Expr::NoMatch)
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}
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None => Ok(Expr::NoMatch),
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}
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}
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pub fn read_from_buffer<T: Read>(&mut self, reader: &mut BufReader<T>) -> Result<Vec<Expr>, String> {
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pub fn read_from_buffer<T: Read>(
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&mut self,
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reader: &mut BufReader<T>,
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) -> Result<Vec<Expr>, String> {
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let mut ast = vec![];
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loop {
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match self.read_expr(reader) {
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Ok(Expr::NoMatch) => break,
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Err(v) => return Err(v),
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Ok(v) => ast.push(v)
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Ok(v) => ast.push(v),
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}
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}
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Ok(ast)
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@ -284,10 +315,8 @@ impl ExprReader {
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let mut buf_reader = BufReader::new(reader);
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self.read_from_buffer(&mut buf_reader)
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}
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}
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pub fn read_string(input: &str) -> Result<Vec<Expr>, String> {
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let mut reader = ExprReader::new();
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reader.read(input)
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