Auto-skip: handle if-else statements (#3367)

Adds auto-skip support for if statements. 

earthly/earthly#3040

inputgraph/inputgraph.go

@@ -187,20 +187,28 @@ func (l *loader) handleWithDocker(ctx context.Context, cmd spec.Command) error {
 }
 
 func (l *loader) handleIf(ctx context.Context, ifStmt spec.IfStatement) error {
-	return errors.Wrap(ErrUnableToDetermineHash, "if not supported")
+	l.hashIfStatement(ifStmt)
+	if err := l.loadBlock(ctx, ifStmt.IfBody); err != nil {
+		return err
+	}
+	if ifStmt.ElseBody != nil {
+		if err := l.loadBlock(ctx, *ifStmt.ElseBody); err != nil {
+			return err
+		}
+	}
+	for _, elseIf := range ifStmt.ElseIf {
+		l.hashElseIf(elseIf)
+		if err := l.loadBlock(ctx, elseIf.Body); err != nil {
+			return err
+		}
+	}
+	return nil
 }
 
 func (l *loader) handleFor(ctx context.Context, forStmt spec.ForStatement) error {
 	return errors.Wrap(ErrUnableToDetermineHash, "for not supported")
 }
 
-func (l *loader) hashWaitStatement(w spec.WaitStatement) {
-	w.SourceLocation = nil
-	l.hasher.HashString("WAIT")
-	l.hasher.HashInt(len(w.Body))
-	l.hasher.HashJSONMarshalled(w.Args)
-}
-
 func (l *loader) handleWait(ctx context.Context, waitStmt spec.WaitStatement) error {
 	l.hashWaitStatement(waitStmt)
 	for _, stmt := range waitStmt.Body {
@@ -247,6 +255,43 @@ func (l *loader) loadBlock(ctx context.Context, b spec.Block) error {
 	return nil
 }
 
+func (l *loader) hashIfStatement(s spec.IfStatement) {
+	s.SourceLocation = nil
+	l.hasher.HashString("IF")
+	l.hasher.HashJSONMarshalled(s.Expression)
+	l.hasher.HashBool(s.ExecMode)
+	l.hasher.HashInt(len(s.IfBody))
+	l.hasher.HashInt(len(s.ElseIf))
+	if s.ElseBody != nil {
+		l.hasher.HashInt(len(*s.ElseBody))
+	}
+}
+
+func (l *loader) hashElseIf(e spec.ElseIf) {
+	e.SourceLocation = nil
+	l.hasher.HashString("ELSE IF")
+	l.hasher.HashJSONMarshalled(e.Expression)
+	l.hasher.HashBool(e.ExecMode)
+	l.hasher.HashInt(len(e.Body))
+}
+
+func (l *loader) hashWaitStatement(w spec.WaitStatement) {
+	w.SourceLocation = nil
+	l.hasher.HashString("WAIT")
+	l.hasher.HashInt(len(w.Body))
+	l.hasher.HashJSONMarshalled(w.Args)
+}
+
+func (l *loader) hashVersion(v spec.Version) {
+	v.SourceLocation = nil
+	l.hasher.HashJSONMarshalled(v)
+}
+
+func (l *loader) hashCommand(cmd spec.Command) {
+	cmd.SourceLocation = nil
+	l.hasher.HashJSONMarshalled(cmd)
+}
+
 func copyVisited(m map[string]struct{}) map[string]struct{} {
 	m2 := map[string]struct{}{}
 	for k := range m {
@@ -284,16 +329,6 @@ func (l *loader) loadTargetFromString(ctx context.Context, targetName string) er
 	return loaderInst.load(ctx)
 }
 
-func (l *loader) hashVersion(v spec.Version) {
-	v.SourceLocation = nil
-	l.hasher.HashJSONMarshalled(v)
-}
-
-func (l *loader) hashCommand(cmd spec.Command) {
-	cmd.SourceLocation = nil
-	l.hasher.HashJSONMarshalled(cmd)
-}
-
 func (l *loader) findProject(ctx context.Context) (org, project string, err error) {
 	if l.target.IsRemote() {
 		return "", "", ErrRemoteNotSupported

tests/autoskip/Earthfile

@@ -11,6 +11,7 @@ test-all:
     BUILD +test-auto-skip-with-subdir
     BUILD +test-auto-skip-requires-project
     BUILD +test-auto-skip-wait
+    BUILD +test-auto-skip-if-else
 
 test-auto-skip:
     RUN echo hello > my-file
@@ -46,6 +47,10 @@ test-auto-skip-wait:
     DO --pass-args +RUN_EARTHLY_ARGS --earthfile=wait.earth --target=+test --output_contains="not skipped"
     DO --pass-args +RUN_EARTHLY_ARGS --earthfile=wait.earth --target=+test --output_contains="ec3d61867365de2deda79ce06f7afa849b765bb1"
 
+test-auto-skip-if-else:
+    DO --pass-args +RUN_EARTHLY_ARGS --earthfile=if-else.earth --target=+test --output_contains="condition ok"
+    DO --pass-args +RUN_EARTHLY_ARGS --earthfile=if-else.earth --target=+test --output_contains="d7ba3699b3342c386fd40b3368c167898ae58f2a"
+
 RUN_EARTHLY_ARGS:
     COMMAND
     ARG earthfile

tests/autoskip/if-else.earth

@@ -0,0 +1,14 @@
+VERSION 0.7
+
+PROJECT earthly-technologies/core
+
+FROM alpine
+
+test:
+    IF [ true ]
+       RUN echo "condition ok"
+    ELSE IF [ false ]
+       RUN echo "never"
+    ELSE
+       RUN echo "nope"
+    END

util/buildkitskipper/hasher/hasher.go

@@ -40,6 +40,10 @@ func (h *Hasher) HashJSONMarshalled(v any) {
 	h.HashBytes(dt)
 }
 
+func (h *Hasher) HashBool(v bool) {
+	h.HashBytes([]byte(fmt.Sprintf("bool:%t", v)))
+}
+
 func (h *Hasher) HashString(s string) {
 	h.HashBytes([]byte(fmt.Sprintf("str:%s", s)))
 }