From bbf2970c4ec1fd29ce1b2b3c78dc67dce81caeaa Mon Sep 17 00:00:00 2001
From: Eduard Urbach <eduard@urbach.dev>
Date: Wed, 26 Feb 2025 20:02:53 +0100
Subject: [PATCH] Simplified constant folding

---
 src/core/Fold.go             | 24 ++----------------------
 src/core/FoldConstant.go     | 23 +++++++++++++++++++++++
 src/core/FoldLeaf.go         | 17 +++++++++++++++++
 src/expression/Expression.go |  5 ++---
 src/expression/Foldable.go   |  7 +++++++
 5 files changed, 51 insertions(+), 25 deletions(-)
 create mode 100644 src/core/FoldConstant.go
 create mode 100644 src/core/FoldLeaf.go
 create mode 100644 src/expression/Foldable.go

diff --git a/src/core/Fold.go b/src/core/Fold.go
index 768f2ec..11ae861 100644
--- a/src/core/Fold.go
+++ b/src/core/Fold.go
@@ -17,31 +17,11 @@ func (f *Function) Fold(expr *expression.Expression) error {
 	}
 
 	if expr.IsLeaf() {
-		if expr.Token.IsNumeric() {
-			value, err := f.ToNumber(expr.Token)
-			expr.Value = value
-			expr.IsFolded = true
-			return err
-		}
-
-		return nil
+		return f.FoldLeaf(expr)
 	}
 
 	if expr.Token.Kind == token.Period {
-		left := expr.Children[0]
-		leftText := left.Token.Text(f.File.Bytes)
-		right := expr.Children[1]
-		rightText := right.Token.Text(f.File.Bytes)
-		constant, isConst := f.All.Constants[f.Package+"."+leftText+"."+rightText]
-
-		if !isConst {
-			return nil
-		}
-
-		value, err := ToNumber(constant.Token, constant.File)
-		expr.Value = value
-		expr.IsFolded = true
-		return err
+		return f.FoldConstant(expr)
 	}
 
 	canFold := true
diff --git a/src/core/FoldConstant.go b/src/core/FoldConstant.go
new file mode 100644
index 0000000..39c0c23
--- /dev/null
+++ b/src/core/FoldConstant.go
@@ -0,0 +1,23 @@
+package core
+
+import (
+	"git.urbach.dev/cli/q/src/expression"
+)
+
+// FoldConstant tries to find a constant that can be folded.
+func (f *Function) FoldConstant(expr *expression.Expression) error {
+	left := expr.Children[0]
+	right := expr.Children[1]
+	leftText := left.Token.Text(f.File.Bytes)
+	rightText := right.Token.Text(f.File.Bytes)
+	constant, exists := f.All.Constants[f.Package+"."+leftText+"."+rightText]
+
+	if !exists {
+		return nil
+	}
+
+	value, err := ToNumber(constant.Token, constant.File)
+	expr.Value = value
+	expr.IsFolded = true
+	return err
+}
diff --git a/src/core/FoldLeaf.go b/src/core/FoldLeaf.go
new file mode 100644
index 0000000..c989bf7
--- /dev/null
+++ b/src/core/FoldLeaf.go
@@ -0,0 +1,17 @@
+package core
+
+import (
+	"git.urbach.dev/cli/q/src/expression"
+)
+
+// FoldLeaf tries to fold a leaf expression.
+func (f *Function) FoldLeaf(expr *expression.Expression) error {
+	if !expr.Token.IsNumeric() {
+		return nil
+	}
+
+	value, err := f.ToNumber(expr.Token)
+	expr.Value = value
+	expr.IsFolded = true
+	return err
+}
diff --git a/src/expression/Expression.go b/src/expression/Expression.go
index aecaa77..a76569a 100644
--- a/src/expression/Expression.go
+++ b/src/expression/Expression.go
@@ -11,9 +11,8 @@ type Expression struct {
 	Parent     *Expression
 	Children   []*Expression
 	Token      token.Token
-	Value      int
 	Precedence int8
-	IsFolded   bool
+	Foldable
 }
 
 // New creates a new expression.
@@ -62,8 +61,8 @@ func (expr *Expression) Reset() {
 	}
 
 	expr.Token.Reset()
-	expr.Value = 0
 	expr.Precedence = 0
+	expr.Value = 0
 	expr.IsFolded = false
 }
 
diff --git a/src/expression/Foldable.go b/src/expression/Foldable.go
new file mode 100644
index 0000000..c225d80
--- /dev/null
+++ b/src/expression/Foldable.go
@@ -0,0 +1,7 @@
+package expression
+
+// Foldable has optional fields that are used for constant folding later.
+type Foldable struct {
+	Value    int
+	IsFolded bool
+}