1 files changed, 90 insertions, 8 deletions
diff --git a/build/instructions.go b/build/instructions.go
index e807b5b..5c12796 100644
--- a/build/instructions.go
+++ b/build/instructions.go
@@ -1,14 +1,96 @@
 package build
 
-type InstructionType int
-
-const (
-	Run InstructionType = iota
-	Copy
-	Env
+import (
+	"fmt"
+	"sort"
+	"strconv"
+	"strings"
 )
 
-type Instruction struct {
-	Type      InstructionType
+type Instruction interface {
+	Compile() []string
+}
+
+type Run struct {
+	Command   string
 	Arguments []string
 }
+
+func (run Run) Compile() []string {
+	numInnerArgs := strings.Count(run.Command, `%`) - strings.Count(run.Command, `%%`)
+	command := sprintf(run.Command, run.Arguments[0:numInnerArgs])
+
+	if len(run.Arguments) > numInnerArgs {
+		command += " " + strings.Join(quoteAll(run.Arguments[numInnerArgs:]), " ")
+	}
+
+	return []string{command}
+}
+
+type RunAll struct {
+	Runs []Run
+}
+
+func (runAll RunAll) Compile() []string {
+	commands := make([]string, len(runAll.Runs))
+
+	for i, run := range runAll.Runs {
+		commands[i] = run.Compile()[0]
+	}
+
+	return []string{strings.Join(commands, " && ")}
+}
+
+type Copy struct {
+	Sources     []string
+	Destination string
+}
+
+func (copy Copy) Compile() []string {
+	return append(quoteAll(copy.Sources), quote(copy.Destination))
+}
+
+type Env struct {
+	Definitions map[string]string
+}
+
+func (env Env) Compile() []string {
+	defs := make([]string, 0, len(env.Definitions))
+	names := make([]string, 0, len(env.Definitions))
+
+	for name := range env.Definitions {
+		names = append(names, name)
+	}
+
+	sort.Strings(names)
+
+	for _, name := range names {
+		defs = append(defs, name+"="+quote(env.Definitions[name]))
+	}
+
+	return defs
+}
+
+func quote(arg string) string {
+	return strconv.Quote(arg)
+}
+
+func quoteAll(arguments []string) []string {
+	quoted := make([]string, len(arguments))
+
+	for i, arg := range arguments {
+		quoted[i] = quote(arg)
+	}
+
+	return quoted
+}
+
+func sprintf(format string, arguments []string) string {
+	args := make([]interface{}, len(arguments))
+
+	for i, v := range arguments {
+		args[i] = quote(v)
+	}
+
+	return fmt.Sprintf(format, args...)
+}