From c2be740ad4f06c7be3c395340f140ad440f924f7 Mon Sep 17 00:00:00 2001
From: JT <jonathan.d.turner@gmail.com>
Date: Sat, 31 Jul 2021 16:04:42 +1200
Subject: [PATCH] def predecl

---
 src/parser.rs       | 49 +++++++++++++++++++++++++++++++++++++++------
 src/parser_state.rs | 17 ++++++++++++++++
 src/tests.rs        | 13 ++++++++----
 3 files changed, 69 insertions(+), 10 deletions(-)

diff --git a/src/parser.rs b/src/parser.rs
index b3217a9dc4..6913328878 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -2090,6 +2090,33 @@ impl<'a> ParserWorkingSet<'a> {
         }
     }
 
+    pub fn parse_def_predecl(&mut self, spans: &[Span]) {
+        let name = self.get_span_contents(spans[0]);
+
+        if name == b"def" && spans.len() >= 4 {
+            //FIXME: don't use expect here
+            let (name_expr, ..) = self.parse_string(spans[1]);
+            let name = name_expr
+                .as_string()
+                .expect("internal error: expected def name");
+
+            self.enter_scope();
+            let (sig, ..) = self.parse_signature(spans[2]);
+            let mut signature = sig
+                .as_signature()
+                .expect("internal error: expected param list");
+            self.exit_scope();
+
+            signature.name = name;
+            let decl = Declaration {
+                signature,
+                body: None,
+            };
+
+            self.add_decl(decl);
+        }
+    }
+
     pub fn parse_def(&mut self, spans: &[Span]) -> (Statement, Option<ParseError>) {
         let mut error = None;
         let name = self.get_span_contents(spans[0]);
@@ -2102,11 +2129,16 @@ impl<'a> ParserWorkingSet<'a> {
                 .expect("internal error: expected def name");
             error = error.or(err);
 
+            let decl_id = self
+                .find_decl(name.as_bytes())
+                .expect("internal error: predeclaration failed to add definition");
+
             self.enter_scope();
             let (sig, err) = self.parse_signature(spans[2]);
             let mut signature = sig
                 .as_signature()
                 .expect("internal error: expected param list");
+            signature.name = name;
             error = error.or(err);
 
             let (block, err) = self.parse_block_expression(spans[3]);
@@ -2115,13 +2147,10 @@ impl<'a> ParserWorkingSet<'a> {
             let block_id = block.as_block().expect("internal error: expected block");
             error = error.or(err);
 
-            signature.name = name;
-            let decl = Declaration {
-                signature,
-                body: Some(block_id),
-            };
+            let declaration = self.get_decl_mut(decl_id);
+            declaration.signature = signature;
+            declaration.body = Some(block_id);
 
-            self.add_decl(decl);
             let def_decl_id = self
                 .find_decl(b"def")
                 .expect("internal error: missing def command");
@@ -2211,6 +2240,14 @@ impl<'a> ParserWorkingSet<'a> {
 
         let mut block = Block::new();
 
+        // Pre-declare any definition so that definitions
+        // that share the same block can see each other
+        for pipeline in &lite_block.block {
+            if pipeline.commands.len() == 1 {
+                self.parse_def_predecl(&pipeline.commands[0].parts);
+            }
+        }
+
         for pipeline in &lite_block.block {
             if pipeline.commands.len() > 1 {
                 let mut output = vec![];
diff --git a/src/parser_state.rs b/src/parser_state.rs
index 72c19cb754..6ed8d98b29 100644
--- a/src/parser_state.rs
+++ b/src/parser_state.rs
@@ -306,6 +306,11 @@ impl<'a> ParserWorkingSet<'a> {
         None
     }
 
+    pub fn update_decl(&mut self, decl_id: usize, block: Option<BlockId>) {
+        let decl = self.get_decl_mut(decl_id);
+        decl.body = block;
+    }
+
     pub fn contains_decl_partial_match(&self, name: &[u8]) -> bool {
         for scope in self.delta.scope.iter().rev() {
             for decl in &scope.decls {
@@ -401,6 +406,18 @@ impl<'a> ParserWorkingSet<'a> {
         }
     }
 
+    pub fn get_decl_mut(&mut self, decl_id: DeclId) -> &mut Declaration {
+        let num_permanent_decls = self.permanent_state.num_decls();
+        if decl_id < num_permanent_decls {
+            panic!("internal error: can only mutate declarations in working set")
+        } else {
+            self.delta
+                .decls
+                .get_mut(decl_id - num_permanent_decls)
+                .expect("internal error: missing declaration")
+        }
+    }
+
     pub fn get_block(&self, block_id: BlockId) -> &Block {
         let num_permanent_blocks = self.permanent_state.num_blocks();
         if block_id < num_permanent_blocks {
diff --git a/src/tests.rs b/src/tests.rs
index 2cdd1d77dc..22028ce3e2 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -78,7 +78,7 @@ fn if_test2() -> TestResult {
 }
 
 #[test]
-fn no_leak1() -> TestResult {
+fn no_scope_leak1() -> TestResult {
     fail_test(
         "if $false { let $x = 10 } else { let $x = 20 }; $x",
         "VariableNotFound",
@@ -86,7 +86,7 @@ fn no_leak1() -> TestResult {
 }
 
 #[test]
-fn no_leak2() -> TestResult {
+fn no_scope_leak2() -> TestResult {
     fail_test(
         "def foo [] { $x }; def bar [] { let $x = 10; foo }; bar",
         "VariableNotFound",
@@ -94,7 +94,7 @@ fn no_leak2() -> TestResult {
 }
 
 #[test]
-fn no_leak3() -> TestResult {
+fn no_scope_leak3() -> TestResult {
     run_test(
         "def foo [$x] { $x }; def bar [] { let $x = 10; foo 20}; bar",
         "20",
@@ -102,7 +102,7 @@ fn no_leak3() -> TestResult {
 }
 
 #[test]
-fn no_leak4() -> TestResult {
+fn no_scope_leak4() -> TestResult {
     run_test(
         "def foo [$x] { $x }; def bar [] { let $x = 10; (foo 20) + $x}; bar",
         "30",
@@ -113,3 +113,8 @@ fn no_leak4() -> TestResult {
 fn simple_var_closing() -> TestResult {
     run_test("let $x = 10; def foo [] { $x }; foo", "10")
 }
+
+#[test]
+fn predecl_check() -> TestResult {
+    run_test("def bob [] { sam }; def sam [] { 3 }; bob", "3")
+}