109 lines
3.1 KiB
Rust
109 lines
3.1 KiB
Rust
/** Serene --- Yet an other Lisp
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*
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* Copyright (c) 2020 Sameer Rahmani <lxsameer@gnu.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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use crate::ast::{Expr, Expression, Location, PossibleExpr};
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use crate::errors::err;
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use crate::runtime::RT;
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use crate::scope::Scope;
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use std::fmt;
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#[derive(Debug, Clone)]
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pub struct Symbol {
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pub name: String,
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/// This field holds the ns specifier part of the symbol. For example
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/// in case of `somens/somesym`, this field will hold `somens`.
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target_ns: Option<String>,
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/// Name of the namespace which this symbol is in. It doesn't mean
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/// the namespace which this symbol is defined. For example Let's
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/// say we're in ns A, and there is a sumbol `B/x`. This symbol
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/// refers to the symbol `x` in ns B and it's not the same as
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/// the symbol `x` in ns B. They are two different symbols pointing
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/// to the same value. the `ns` value of the one in ns A would be `A`
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/// and the one in B would be `B`.
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ns: Option<String>,
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}
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impl Symbol {
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pub fn new(name: String, target_ns: Option<String>) -> Symbol {
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Symbol {
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name,
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target_ns,
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ns: None,
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}
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}
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pub fn is_ns_qualified(&self) -> bool {
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!self.target_ns.is_none()
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}
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pub fn is_def(&self) -> bool {
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self.name == "def"
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}
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/// Only clones the symbol if ns isn't set yet.
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pub fn clone_with_ns(self, ns_name: String) -> Symbol {
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if let Some(_) = self.ns {
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return self;
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}
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Symbol {
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ns: Some(ns_name),
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..self.clone()
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}
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}
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}
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impl PartialEq for Symbol {
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fn eq(&self, other: &Self) -> bool {
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self.name == other.name
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}
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}
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impl Eq for Symbol {}
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impl Expression for Symbol {
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fn eval(&self, rt: &RT, scope: &Scope) -> PossibleExpr {
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if self.is_ns_qualified() {
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return rt
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.current_ns()
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.lookup_external(&self.target_ns.clone().unwrap(), &self.name);
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}
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match scope.lookup(&self.name) {
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Some(e) => Ok(e.expr.clone()),
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_ => Err(err(format!(
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"Undefined binding {} in ns '{}' at {}",
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self,
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self.ns.clone().unwrap(),
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self.location()
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))),
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}
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}
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}
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impl fmt::Display for Symbol {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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match &self.ns {
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Some(n) => write!(f, "#'{}/{}", &n, &self.name),
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_ => panic!(
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"Displaying symbol '{:?}' without evaluating it.",
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&self.name
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),
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}
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}
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}
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