From c9229439f74282db466673a468642c27c6d57e44 Mon Sep 17 00:00:00 2001
From: Mike Farah <mikefarah@gmail.com>
Date: Mon, 30 Nov 2020 16:35:21 +1100
Subject: [PATCH] added exit status

---
 cmd/constant.go                 | 2 +-
 cmd/evaluate_all_command.go     | 7 ++++++-
 cmd/evalute_sequence_command.go | 8 +++++++-
 cmd/root.go                     | 1 +
 pkg/yqlib/printer.go            | 9 +++++++++
 5 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/cmd/constant.go b/cmd/constant.go
index 98e20796..fb8f94d4 100644
--- a/cmd/constant.go
+++ b/cmd/constant.go
@@ -5,7 +5,7 @@ var unwrapScalar = true
 var writeInplace = false
 var outputToJSON = false
 
-// var exitStatus = false
+var exitStatus = false
 var forceColor = false
 var forceNoColor = false
 var colorsEnabled = false
diff --git a/cmd/evaluate_all_command.go b/cmd/evaluate_all_command.go
index ec4bf20a..5bf24654 100644
--- a/cmd/evaluate_all_command.go
+++ b/cmd/evaluate_all_command.go
@@ -1,6 +1,7 @@
 package cmd
 
 import (
+	"errors"
 	"fmt"
 	"os"
 
@@ -24,6 +25,7 @@ yq es -n '{"a": "b"}'
 	return cmdEvalAll
 }
 func evaluateAll(cmd *cobra.Command, args []string) error {
+	cmd.SilenceUsage = true
 	// 0 args, read std in
 	// 1 arg, null input, process expression
 	// 1 arg, read file in sequence
@@ -81,6 +83,9 @@ func evaluateAll(cmd *cobra.Command, args []string) error {
 
 	completedSuccessfully = err == nil
 
-	cmd.SilenceUsage = true
+	if err == nil && exitStatus && !printer.PrintedAnything() {
+		return errors.New("no matches found")
+	}
+
 	return err
 }
diff --git a/cmd/evalute_sequence_command.go b/cmd/evalute_sequence_command.go
index cdd70bd0..45625207 100644
--- a/cmd/evalute_sequence_command.go
+++ b/cmd/evalute_sequence_command.go
@@ -1,6 +1,7 @@
 package cmd
 
 import (
+	"errors"
 	"fmt"
 	"os"
 
@@ -24,6 +25,7 @@ yq es -n '{"a": "b"}'
 	return cmdEvalSequence
 }
 func evaluateSequence(cmd *cobra.Command, args []string) error {
+	cmd.SilenceUsage = true
 	// 0 args, read std in
 	// 1 arg, null input, process expression
 	// 1 arg, read file in sequence
@@ -81,6 +83,10 @@ func evaluateSequence(cmd *cobra.Command, args []string) error {
 		err = streamEvaluator.EvaluateFiles(args[0], args[1:], printer)
 	}
 	completedSuccessfully = err == nil
-	cmd.SilenceUsage = true
+
+	if err == nil && exitStatus && !printer.PrintedAnything() {
+		return errors.New("no matches found")
+	}
+
 	return err
 }
diff --git a/cmd/root.go b/cmd/root.go
index 05878555..9dbe6521 100644
--- a/cmd/root.go
+++ b/cmd/root.go
@@ -47,6 +47,7 @@ func New() *cobra.Command {
 	rootCmd.PersistentFlags().IntVarP(&indent, "indent", "I", 2, "sets indent level for output")
 	rootCmd.Flags().BoolVarP(&version, "version", "V", false, "Print version information and quit")
 	rootCmd.PersistentFlags().BoolVarP(&writeInplace, "inplace", "i", false, "update the yaml file inplace of first yaml file given.")
+	rootCmd.PersistentFlags().BoolVarP(&exitStatus, "exit-status", "e", false, "set exit status if there are no matches or null or false is returned")
 
 	rootCmd.PersistentFlags().BoolVarP(&forceColor, "colors", "C", false, "force print with colors")
 	rootCmd.PersistentFlags().BoolVarP(&forceNoColor, "no-colors", "M", false, "force print with no colors")
diff --git a/pkg/yqlib/printer.go b/pkg/yqlib/printer.go
index 6c7f41e7..1da0728a 100644
--- a/pkg/yqlib/printer.go
+++ b/pkg/yqlib/printer.go
@@ -10,6 +10,7 @@ import (
 
 type Printer interface {
 	PrintResults(matchingNodes *list.List) error
+	PrintedAnything() bool
 }
 
 type resultsPrinter struct {
@@ -21,6 +22,7 @@ type resultsPrinter struct {
 	writer             io.Writer
 	firstTimePrinting  bool
 	previousDocIndex   uint
+	printedMatches     bool
 }
 
 func NewPrinter(writer io.Writer, outputToJSON bool, unwrapScalar bool, colorsEnabled bool, indent int, printDocSeparators bool) Printer {
@@ -35,7 +37,14 @@ func NewPrinter(writer io.Writer, outputToJSON bool, unwrapScalar bool, colorsEn
 	}
 }
 
+func (p *resultsPrinter) PrintedAnything() bool {
+	return p.printedMatches
+}
+
 func (p *resultsPrinter) printNode(node *yaml.Node, writer io.Writer) error {
+	p.printedMatches = p.printedMatches || (node.Tag != "!!null" &&
+		(node.Tag != "!!bool" || node.Value != "false"))
+
 	var encoder Encoder
 	if node.Kind == yaml.ScalarNode && p.unwrapScalar && !p.outputToJSON {
 		return p.writeString(writer, node.Value+"\n")