From da0d0dfc18b69427ffc5210adf3cee351017080d Mon Sep 17 00:00:00 2001
From: Brian Picciano <mediocregopher@gmail.com>
Date: Thu, 28 Jul 2016 13:57:17 -0600
Subject: [PATCH] got macro statements working

---
 expr/expr.go   | 34 ++++++++++++++++++++++++++--------
 expr/macros.go | 34 ++++++++++++++++++++++++++++++++++
 main.go        | 20 +++++---------------
 3 files changed, 65 insertions(+), 23 deletions(-)
 create mode 100644 expr/macros.go

diff --git a/expr/expr.go b/expr/expr.go
index d201326..3e5db02 100644
--- a/expr/expr.go
+++ b/expr/expr.go
@@ -26,7 +26,7 @@ type Actual interface {
 	// are equal.
 	Equal(Actual) bool
 
-	// Initializes an llvm.Value and returns it
+	// Initializes an llvm.Value and returns it.
 	LLVMVal(llvm.Builder) llvm.Value
 }
 
@@ -148,7 +148,7 @@ func (m Macro) Equal(e Actual) bool {
 }
 
 func (m Macro) LLVMVal(builder llvm.Builder) llvm.Value {
-	return llvm.Value{}
+	panic("Macros have no inherent LLVMVal")
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -188,6 +188,8 @@ func (tup Tuple) LLVMVal(builder llvm.Builder) llvm.Value {
 // Pipe represents a set of expressions which operate on values and return new
 // values. The inputs of one expression in the pipe is the output of the
 // previous expression
+//
+// TODO remove this, sorry Pipe
 type Pipe []Expr
 
 func (p Pipe) String() string {
@@ -222,22 +224,37 @@ func (p Pipe) LLVMVal(builder llvm.Builder) llvm.Value {
 // used as the input to the pipe, and the output of the pipe is the output of
 // the statement
 type Statement struct {
-	in   Expr
-	pipe Pipe
+	In Expr
+	To Expr
 }
 
 func (s Statement) String() string {
-	return fmt.Sprintf("(%v > %s)", s.in.Actual, s.pipe.String())
+	return fmt.Sprintf("(%v > %s)", s.In.Actual, s.To.Actual)
 }
 
 // Equal implements the Actual method
 func (s Statement) Equal(e Actual) bool {
 	ss, ok := e.(Statement)
-	return ok && s.in.Actual.Equal(ss.in.Actual) && s.pipe.Equal(ss.pipe)
+	return ok && s.In.Actual.Equal(ss.In.Actual) && s.To.Actual.Equal(ss.To.Actual)
 }
 
 func (s Statement) LLVMVal(builder llvm.Builder) llvm.Value {
-	return llvm.Value{}
+	m, ok := s.To.Actual.(Macro)
+	if !ok {
+		// TODO proper error
+		panic("statement To is not a macro")
+	}
+	fn, ok := macros[m]
+	if !ok {
+		// TODO proper error
+		panic(fmt.Sprintf("unknown macro %q", m))
+	}
+	newe, err := fn(s.In)
+	if err != nil {
+		// TODO proper error
+		panic(err)
+	}
+	return newe.LLVMVal(builder)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -513,7 +530,8 @@ func parseConnectingPunct(toks []lexer.Token, root Expr) (Expr, []lexer.Token, e
 		if !ok {
 			pipe = Pipe{expr}
 		}
-		return Expr{Token: root.Token, Actual: Statement{in: root, pipe: pipe}}, toks, nil
+		pipeExpr := Expr{Actual: pipe, Token: expr.Token}
+		return Expr{Token: root.Token, Actual: Statement{In: root, To: pipeExpr}}, toks, nil
 	}
 
 	return root, toks, nil
diff --git a/expr/macros.go b/expr/macros.go
new file mode 100644
index 0000000..401f8b3
--- /dev/null
+++ b/expr/macros.go
@@ -0,0 +1,34 @@
+package expr
+
+import (
+	"errors"
+
+	"llvm.org/llvm/bindings/go/llvm"
+)
+
+type addActual []Expr
+
+func (aa addActual) Equal(Actual) bool { return false }
+
+func (aa addActual) LLVMVal(builder llvm.Builder) llvm.Value {
+	a := builder.CreateLoad(aa[0].LLVMVal(builder), "")
+	for i := range aa[1:] {
+		b := builder.CreateLoad(aa[i+1].LLVMVal(builder), "")
+		a = builder.CreateAdd(a, b, "")
+	}
+	return a
+}
+
+var macros = map[Macro]func(Expr) (Expr, error){
+	"add": func(e Expr) (Expr, error) {
+		tup, ok := e.Actual.(Tuple)
+		if !ok {
+			// TODO proper error
+			return Expr{}, errors.New("add only accepts a tuple")
+		}
+		return Expr{
+			Actual: addActual(tup),
+			Token:  e.Token,
+		}, nil
+	},
+}
diff --git a/main.go b/main.go
index 1d85739..e33217d 100644
--- a/main.go
+++ b/main.go
@@ -8,19 +8,6 @@ import (
 	"llvm.org/llvm/bindings/go/llvm"
 )
 
-type addActual []expr.Expr
-
-func (aa addActual) Equal(expr.Actual) bool { return false }
-
-func (aa addActual) LLVMVal(builder llvm.Builder) llvm.Value {
-	a := builder.CreateLoad(aa[0].LLVMVal(builder), "")
-	for i := range aa[1:] {
-		b := builder.CreateLoad(aa[i+1].LLVMVal(builder), "")
-		a = builder.CreateAdd(a, b, "")
-	}
-	return a
-}
-
 func main() {
 	//ee, err := expr.Parse(os.Stdin)
 	//if err != nil {
@@ -47,8 +34,11 @@ func main() {
 	a := expr.Expr{Actual: expr.Int(1)}
 	b := expr.Expr{Actual: expr.Int(2)}
 	c := expr.Expr{Actual: expr.Int(3)}
-	add := addActual{a, b, c}
-	result := add.LLVMVal(builder)
+	tup := expr.Expr{Actual: expr.Tuple{a, b, c}}
+	addMacro := expr.Expr{Actual: expr.Macro("add")}
+	stmt := expr.Expr{Actual: expr.Statement{In: tup, To: addMacro}}
+
+	result := stmt.LLVMVal(builder)
 	builder.CreateRet(result)
 
 	// verify it's all good