parent
5169227499
commit
784f3f2c10
GPG Key ID:
284488987C31F630
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//! Execution environment for repl
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use super::*;
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use std::str::FromStr;
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use std::collections::{BTreeMap, HashMap};
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#[derive(Debug)]
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pub struct Lexenv
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{
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/// Maps symbol name to value in generations.
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kvstack: BTreeMap<usize, HashMap<String, Value>>,
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/// Current generation of the satck
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current_generation: usize,
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}
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impl Lexenv
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{
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/// The generation number of the current level.
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pub fn depth(&self) -> usize
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{
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self.current_generation
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}
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/// Create a new empty lexenv
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pub fn new() -> Self
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{
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Self {
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kvstack: BTreeMap::new(),
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current_generation: 0,
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}
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}
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/// All valid symbols at this level.
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///
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/// # Ordering
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/// Each symbol's level will appear in the order from level 0 to the current level, however the order of intra-level symbols is undefined.
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pub fn symbols(&self) -> impl Iterator<Item = &'_ Value> + '_
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{
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self.kvstack.range(0..=self.current_generation).flat_map(|(_, v)| v.values())
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}
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/// All valid symbols **in** this level.
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pub fn symbols_local(&self) -> impl Iterator<Item = &'_ Value> + '_
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{
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OptionIterator::from(self.kvstack.get(&self.current_generation).map(|x| x.values()))
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}
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/// Remove the current level, but leave its memory allocated for further use.
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pub fn pop(&mut self)
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{
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self.kvstack.entry(self.current_generation).or_insert_with(|| HashMap::new()).clear();
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if self.current_generation > 0 {
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self.current_generation-=1;
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}
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}
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/// Remove a symbol from the **current** level.
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pub fn remove(&mut self, name: &str) -> Option<Value>
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{
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self.kvstack.entry(self.current_generation).or_insert_with(|| HashMap::new()).remove(name)
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}
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/// Insert a new value mapping into the current level.
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pub fn insert(&mut self, name: String, value: Value)
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{
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self.kvstack.entry(self.current_generation).or_insert_with(|| HashMap::new()).insert(name, value);
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}
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/// Look up a symbol in this or any of the above levels.
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pub fn lookup(&self, name: &str) -> Option<&Value>
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{
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for (_, lvmap) in self.kvstack.range(0..=self.current_generation).rev()
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{
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let m = lvmap.get(name);
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if m.is_some() {
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return m;
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}
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}
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None
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}
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/// Look up a symbol in this level.
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pub fn lookup_local(&self, name: &str) -> Option<&Value>
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{
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self.kvstack.get(&self.current_generation).map(|map| map.get(name)).flatten()
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}
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/// Create a new, empty level.
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pub fn push(&mut self)
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{
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self.current_generation+=1;
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}
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/// Remove the current level, deallocating any memory it was using.
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pub fn pop_clear(&mut self)
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{
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if self.current_generation > 0 {
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self.kvstack.remove(&self.current_generation);
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self.current_generation -=1;
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} else {
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self.kvstack.entry(0).or_insert_with(|| HashMap::new()).clear();
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}
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}
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}
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/// The value type
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#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
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pub enum Value
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{
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String(String),
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Symbol(String),
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List(Vec<Value>),
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}
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impl Value
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{
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/// Parse from an iterator of `char`s.
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pub fn parse_chars<T>(ch: &mut T) -> Result<Self, ValueParseError>
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where T: Iterator<Item = char>
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{
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match ch.next()
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{
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Some('(') => {
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todo!("list");
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},
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Some('"') => {
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todo!("string");
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},
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Some(first_chr) => {
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todo!("symbol");
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},
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_ => Err(ValueParseError(String::default())),
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}
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}
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/// Parse a `Value` from this string and then return the rest of the string.
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#[deprecated]
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pub fn parse_running(s: &str) -> Result<(Self, &'_ str), ValueParseError>
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{
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match s.trim().as_bytes()
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{
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& [b'(', ..] => {
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todo!("list");
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},
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& [b'"', ..] => {
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todo!("string");
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},
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_ => {
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todo!("shmbol");
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}
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}
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}
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}
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impl FromStr for Value
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{
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type Err = ValueParseError;
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fn from_str(s: &str) -> Result<Self, Self::Err> {
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Self::parse_running(s).map(|(x, _)| x)
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}
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}
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impl Value
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{
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pub fn try_as_symbol(&self) -> Result<&str, ValueTypeError>
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{
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match self {
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Self::Symbol(s) => Ok(&s[..]),
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_ => Err(ValueTypeError::Symbol),
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}
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}
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pub fn try_as_string(&self) -> Result<&str, ValueTypeError>
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{
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match self {
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Self::Symbol(s) |
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Self::String(s) => Ok(&s[..]),
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_ => Err(ValueTypeError::String),
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}
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}
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pub fn try_as_list(&self) -> Result<&[Value], ValueTypeError>
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{
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match self {
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Self::List(l) => Ok(&l[..]),
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_ => Err(ValueTypeError::List),
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}
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}
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pub fn as_symbol(&self) -> Option<&str>
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{
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match self {
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Self::Symbol(s) => Some(&s[..]),
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_ => None,
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}
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}
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pub fn as_string(&self) -> Option<&str>
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{
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match self {
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Self::Symbol(s) |
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Self::String(s) => Some(&s[..]),
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_ => None,
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}
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}
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pub fn as_list(&self) -> Option<&[Value]>
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{
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match self {
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Self::List(l) => Some(&l[..]),
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_ => None,
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}
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}
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}
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/// Error when using `try_as_*` functions on `Value`.
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#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Copy)]
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pub enum ValueTypeError
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{
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Symbol,
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String,
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List,
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}
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/// Error when parsing a `Value` from a stirng.
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#[derive(Debug)]
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pub struct ValueParseError(String);
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impl error::Error for ValueParseError{}
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impl fmt::Display for ValueParseError
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{
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
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{
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write!(f, "cannot parse {:?}", self.0)
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}
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}
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impl error::Error for ValueTypeError{}
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impl fmt::Display for ValueTypeError
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{
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
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{
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write!(f, "type error: expected ")?;
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match self {
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Self::Symbol => write!(f, "symbol"),
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Self::String => write!(f, "string"),
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Self::List => write!(f, "list"),
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}
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}
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}
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@ -0,0 +1,13 @@
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//! Defined commands
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use super::*;
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use env::*;
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use command::*;
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/// Contains all operations
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#[derive(Debug, Clone)]
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pub struct Operations
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{
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}
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