From 73e32252c417717b2387ddbc235c00f09e0f7e34 Mon Sep 17 00:00:00 2001
From: Joscha <joscha@plugh.de>
Date: Fri, 18 Nov 2022 21:40:27 +0100
Subject: [PATCH] Parse table destructuring

---
 src/parser.rs             |  1 +
 src/parser/expr.rs        |  8 +++--
 src/parser/table_destr.rs | 67 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 73 insertions(+), 3 deletions(-)
 create mode 100644 src/parser/table_destr.rs

diff --git a/src/parser.rs b/src/parser.rs
index 6f00075..3d81aa9 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -3,6 +3,7 @@ mod expr;
 mod lit;
 mod suffix;
 mod table_constr;
+mod table_destr;
 mod var;
 
 use chumsky::prelude::*;
diff --git a/src/parser/expr.rs b/src/parser/expr.rs
index 0c0af2e..ab54245 100644
--- a/src/parser/expr.rs
+++ b/src/parser/expr.rs
@@ -8,6 +8,7 @@ use super::basic::{space, Error};
 use super::lit::lit;
 use super::suffix::suffixed;
 use super::table_constr::table_constr;
+use super::table_destr::table_destr;
 use super::var::var;
 
 fn atom_paren(
@@ -30,11 +31,12 @@ fn atom(
     expr: impl Parser<char, Expr, Error = Error> + Clone,
 ) -> impl Parser<char, Expr, Error = Error> {
     let lit = lit(expr.clone()).map(Expr::Lit);
-    let paren = atom_paren(expr.clone());
+    let var = var(expr.clone()).map(Expr::Var);
     let table_constr = table_constr(expr.clone()).map(Expr::TableConstr);
-    let var = var(expr).map(Expr::Var);
+    let table_destr = table_destr(expr.clone()).map(Expr::TableDestr);
+    let paren = atom_paren(expr);
 
-    lit.or(paren).or(table_constr).or(var)
+    lit.or(paren).or(table_destr).or(table_constr).or(var)
 }
 
 pub fn expr(
diff --git a/src/parser/table_destr.rs b/src/parser/table_destr.rs
new file mode 100644
index 0000000..29a8389
--- /dev/null
+++ b/src/parser/table_destr.rs
@@ -0,0 +1,67 @@
+//! Corresponds to `ast::table_constr`.
+
+use chumsky::prelude::*;
+
+use crate::ast::{Expr, TableDestr, TablePattern, TablePatternElem};
+
+use super::basic::{ident, space, Error};
+
+pub fn table_pattern_elem() -> impl Parser<char, TablePatternElem, Error = Error> {
+    let positional = ident().map(TablePatternElem::Positional);
+
+    let named = ident()
+        .then(space())
+        .then_ignore(just(':'))
+        .then(space())
+        .then(ident())
+        .map_with_span(|(((name, s0), s1), ident), span| TablePatternElem::Named {
+            name,
+            s0,
+            s1,
+            ident,
+            span,
+        });
+
+    named.or(positional)
+}
+
+pub fn table_pattern() -> impl Parser<char, TablePattern, Error = Error> {
+    let elem = space()
+        .then(table_pattern_elem())
+        .then(space())
+        .map(|((s0, elem), s1)| (s0, elem, s1));
+
+    let trailing_comma = just(",").ignore_then(space()).or_not();
+
+    let elems = elem.separated_by(just(",")).then(trailing_comma);
+
+    just("{")
+        .ignore_then(elems)
+        .then_ignore(just("}"))
+        .map_with_span(|(elems, trailing_comma), span| TablePattern {
+            elems,
+            trailing_comma,
+            span,
+        })
+}
+
+pub fn table_destr(
+    expr: impl Parser<char, Expr, Error = Error>,
+) -> impl Parser<char, TableDestr, Error = Error> {
+    let local = text::keyword("local").ignore_then(space()).or_not();
+
+    local
+        .then(table_pattern())
+        .then(space())
+        .then_ignore(just('='))
+        .then(space())
+        .then(expr)
+        .map_with_span(|((((local, pattern), s0), s1), value), span| TableDestr {
+            local,
+            pattern,
+            s0,
+            s1,
+            value: Box::new(value),
+            span,
+        })
+}