From 28de155f086f037c988032aea7425e04bc2333ce Mon Sep 17 00:00:00 2001
From: Stephen Chung <Stephen.Chung@intexact.com>
Date: Sat, 14 Nov 2020 19:04:49 +0800
Subject: [PATCH] Add Expr::DynamicConstant.

---
 src/ast.rs      | 12 ++++++++++--
 src/engine.rs   |  1 +
 src/optimize.rs | 22 ++++++++++++++++++++++
 3 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/src/ast.rs b/src/ast.rs
index b0a4ac00..44847ac7 100644
--- a/src/ast.rs
+++ b/src/ast.rs
@@ -860,6 +860,8 @@ pub struct FnCallExpr {
 /// This type is volatile and may change.
 #[derive(Debug, Clone)]
 pub enum Expr {
+    /// Dynamic constant.
+    DynamicConstant(Box<Dynamic>, Position),
     /// Integer constant.
     IntegerConstant(INT, Position),
     /// Floating-point constant.
@@ -929,6 +931,7 @@ impl Expr {
         Some(match self {
             Self::Expr(x) => return x.get_type_id(),
 
+            Self::DynamicConstant(x, _) => x.type_id(),
             Self::IntegerConstant(_, _) => TypeId::of::<INT>(),
             #[cfg(not(feature = "no_float"))]
             Self::FloatConstant(_, _) => TypeId::of::<FLOAT>(),
@@ -957,6 +960,7 @@ impl Expr {
         Some(match self {
             Self::Expr(x) => return x.get_constant_value(),
 
+            Self::DynamicConstant(x, _) => x.as_ref().clone(),
             Self::IntegerConstant(x, _) => (*x).into(),
             #[cfg(not(feature = "no_float"))]
             Self::FloatConstant(x, _) => (*x).into(),
@@ -1004,6 +1008,7 @@ impl Expr {
             #[cfg(not(feature = "no_float"))]
             Self::FloatConstant(_, pos) => *pos,
 
+            Self::DynamicConstant(_, pos) => *pos,
             Self::IntegerConstant(_, pos) => *pos,
             Self::CharConstant(_, pos) => *pos,
             Self::StringConstant(_, pos) => *pos,
@@ -1036,6 +1041,7 @@ impl Expr {
             #[cfg(not(feature = "no_float"))]
             Self::FloatConstant(_, pos) => *pos = new_pos,
 
+            Self::DynamicConstant(_, pos) => *pos = new_pos,
             Self::IntegerConstant(_, pos) => *pos = new_pos,
             Self::CharConstant(_, pos) => *pos = new_pos,
             Self::StringConstant(_, pos) => *pos = new_pos,
@@ -1096,7 +1102,8 @@ impl Expr {
             #[cfg(not(feature = "no_float"))]
             Self::FloatConstant(_, _) => true,
 
-            Self::IntegerConstant(_, _)
+            Self::DynamicConstant(_, _)
+            | Self::IntegerConstant(_, _)
             | Self::CharConstant(_, _)
             | Self::StringConstant(_, _)
             | Self::FnPointer(_, _)
@@ -1129,7 +1136,8 @@ impl Expr {
             #[cfg(not(feature = "no_float"))]
             Self::FloatConstant(_, _) => false,
 
-            Self::IntegerConstant(_, _)
+            Self::DynamicConstant(_, _)
+            | Self::IntegerConstant(_, _)
             | Self::CharConstant(_, _)
             | Self::FnPointer(_, _)
             | Self::In(_, _)
diff --git a/src/engine.rs b/src/engine.rs
index a401160e..d2a5d684 100644
--- a/src/engine.rs
+++ b/src/engine.rs
@@ -1677,6 +1677,7 @@ impl Engine {
         let result = match expr {
             Expr::Expr(x) => self.eval_expr(scope, mods, state, lib, this_ptr, x, level),
 
+            Expr::DynamicConstant(x, _) => Ok(x.as_ref().clone()),
             Expr::IntegerConstant(x, _) => Ok((*x).into()),
             #[cfg(not(feature = "no_float"))]
             Expr::FloatConstant(x, _) => Ok((*x).into()),
diff --git a/src/optimize.rs b/src/optimize.rs
index 11e4fae3..292d3fc1 100644
--- a/src/optimize.rs
+++ b/src/optimize.rs
@@ -17,6 +17,12 @@ use crate::{calc_native_fn_hash, StaticVec};
 #[cfg(not(feature = "no_function"))]
 use crate::ast::ReturnType;
 
+#[cfg(not(feature = "no_index"))]
+use crate::Array;
+
+#[cfg(not(feature = "no_object"))]
+use crate::Map;
+
 use crate::stdlib::{
     boxed::Box,
     hash::{Hash, Hasher},
@@ -523,9 +529,25 @@ fn optimize_expr(expr: &mut Expr, state: &mut State) {
             // lhs[rhs]
             (lhs, rhs) => { optimize_expr(lhs, state); optimize_expr(rhs, state); }
         },
+        // [ constant .. ]
+        #[cfg(not(feature = "no_index"))]
+        Expr::Array(a, pos) if a.iter().all(Expr::is_constant) => {
+            state.set_dirty();
+            let mut arr: Array = Default::default();
+            arr.extend(mem::take(a).into_iter().map(|expr| expr.get_constant_value().unwrap()));
+            *expr = Expr::DynamicConstant(Box::new(arr.into()), *pos);
+        }
         // [ items .. ]
         #[cfg(not(feature = "no_index"))]
         Expr::Array(a, _) => a.iter_mut().for_each(|expr| optimize_expr(expr, state)),
+        // #{ key:constant, .. }
+        #[cfg(not(feature = "no_object"))]
+        Expr::Map(m, pos) if m.iter().all(|(_, expr)| expr.is_constant()) => {
+            state.set_dirty();
+            let mut map: Map = Default::default();
+            map.extend(mem::take(m).into_iter().map(|(key, expr)| (key.name, expr.get_constant_value().unwrap())));
+            *expr = Expr::DynamicConstant(Box::new(map.into()), *pos);
+        }
         // #{ key:value, .. }
         #[cfg(not(feature = "no_object"))]
         Expr::Map(m, _) => m.iter_mut().for_each(|(_, expr)| optimize_expr(expr, state)),