Implement CLI_PAGER and CLI_AUTOWRAP (#87)

README.md

@@ -38,7 +38,8 @@ You can control your Spanner databases with idiomatic SQL commands.
     * Allow newlines in prompt using `%n`
     * System variables expansion
     * Prompt2 with margin and waiting status
-  * Autowrap and auto adjust column width to fit within terminal width.
+  * Autowrap and auto adjust column width to fit within terminal width when `CLI_AUTOWRAP = TRUE`).
+  * Pager support when `CLI_USE_PAGER = TRUE`
   * Progress bar of DDL execution.
 * Utilize other libraries
   * Dogfooding [`cloudspannerecosystem/memefish`](https://github.com/cloudspannerecosystem/memefish)
@@ -521,6 +522,8 @@ They have almost same semantics with [Spanner JDBC properties](https://cloud.goo
 | CLI_INSECURE              | READ_WRITE | `"FALSE"`                                      |
 | CLI_QUERY_MODE            | READ_WRITE | `"PROFILE"`                                    |
 | CLI_LINT_PLAN             | READ_WRITE | `"TRUE"`                                       |
+| CLI_USE_PAGER             | READ_WRITE | `"TRUE"`                                       |
+| CLI_AUTOWRAP              | READ_WRITE | `"TRUE"`                                       |
 
 ### Embedded Cloud Spanner Emulator
 

cli.go

@@ -27,13 +27,16 @@ import (
 	"log"
 	"math"
 	"os"
+	"os/exec"
 	"os/signal"
 	"regexp"
 	"slices"
 	"strconv"
 	"strings"
 	"time"
 
+	"github.com/kballard/go-shellquote"
+
 	"github.com/nyaosorg/go-readline-ny"
 
 	"github.com/hymkor/go-multiline-ny"
@@ -348,9 +351,12 @@ func (c *Cli) RunInteractive(ctx context.Context) int {
 			c.updateSystemVariables(result)
 		}
 
-		size, _, err := term.GetSize(int(os.Stdout.Fd()))
-		if err != nil {
-			size = math.MaxInt
+		size := math.MaxInt
+		if c.SystemVariables.AutoWrap {
+			size, _, err = term.GetSize(int(os.Stdout.Fd()))
+			if err != nil {
+				size = math.MaxInt
+			}
 		}
 
 		c.PrintResult(size, result, c.SystemVariables.CLIFormat, true)
@@ -426,7 +432,39 @@ func (c *Cli) PrintBatchError(err error) {
 }
 
 func (c *Cli) PrintResult(screenWidth int, result *Result, mode DisplayMode, interactive bool) {
-	printResult(c.SystemVariables.Debug, screenWidth, c.OutStream, result, mode, interactive, c.SystemVariables.Verbose)
+	ostream := c.OutStream
+	var cmd *exec.Cmd
+	if c.SystemVariables.UsePager {
+		pagerpath := cmp.Or(os.Getenv("PAGER"), "less")
+
+		split, err := shellquote.Split(pagerpath)
+		if err != nil {
+			return
+		}
+		cmd = exec.CommandContext(context.Background(), split[0], split[1:]...)
+
+		pr, pw := io.Pipe()
+		ostream = pw
+		cmd.Stdin = pr
+		cmd.Stdout = c.OutStream
+
+		err = cmd.Start()
+		if err != nil {
+			log.Println(err)
+			return
+		}
+		defer func() {
+			err := pw.Close()
+			if err != nil {
+				log.Println(err)
+			}
+			err = cmd.Wait()
+			if err != nil {
+				log.Println(err)
+			}
+		}()
+	}
+	printResult(c.SystemVariables.Debug, screenWidth, ostream, result, mode, interactive, c.SystemVariables.Verbose)
 }
 
 func (c *Cli) PrintProgressingMark() func() {

go.mod

@@ -20,6 +20,7 @@ require (
 	github.com/hymkor/go-multiline-ny v0.17.0
 	github.com/jessevdk/go-flags v1.6.1
 	github.com/k0kubun/pp/v3 v3.4.1
+	github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51
 	github.com/mattn/go-runewidth v0.0.16
 	github.com/ngicks/go-iterator-helper v0.0.15
 	github.com/nyaosorg/go-readline-ny v1.6.2

go.sum

@@ -923,6 +923,7 @@ github.com/k0kubun/pp v3.0.1+incompatible h1:3tqvf7QgUnZ5tXO6pNAZlrvHgl6DvifjDrd
 github.com/k0kubun/pp v3.0.1+incompatible/go.mod h1:GWse8YhT0p8pT4ir3ZgBbfZild3tgzSScAn6HmfYukg=
 github.com/k0kubun/pp/v3 v3.4.1 h1:1WdFZDRRqe8UsR61N/2RoOZ3ziTEqgTPVqKrHeb779Y=
 github.com/k0kubun/pp/v3 v3.4.1/go.mod h1:+SiNiqKnBfw1Nkj82Lh5bIeKQOAkPy6Xw9CAZUZ8npI=
+github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51 h1:Z9n2FFNUXsshfwJMBgNA0RU6/i7WVaAegv3PtuIHPMs=
 github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51/go.mod h1:CzGEWj7cYgsdH8dAjBGEr58BoE7ScuLd+fwFZ44+/x8=
 github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI2bnpBCr8=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=

system_variables.go

@@ -47,6 +47,7 @@ type systemVariables struct {
 	LintPlan                    bool
 	TransactionTag              string
 	RequestTag                  string
+	UsePager                    bool
 
 	// it is internal variable and hidden from system variable statements
 	ProtoDescriptor *descriptorpb.FileDescriptorSet
@@ -58,6 +59,7 @@ type systemVariables struct {
 	CurrentSession  *Session
 	ReadOnly        bool
 	VertexAIProject string
+	AutoWrap        bool
 }
 
 var errIgnored = errors.New("ignored")
@@ -453,6 +455,12 @@ var accessorMap = map[string]accessor{
 		}),
 		Setter: boolSetter(func(sysVars *systemVariables) *bool { return &sysVars.LintPlan }),
 	},
+	"CLI_USE_PAGER": boolAccessor(func(variables *systemVariables) *bool {
+		return &variables.UsePager
+	}),
+	"CLI_AUTOWRAP": boolAccessor(func(variables *systemVariables) *bool {
+		return &variables.AutoWrap
+	}),
 	"CLI_QUERY_MODE": {
 		Getter: func(this *systemVariables, name string) (map[string]string, error) {
 			if this.QueryMode == nil {
@@ -549,6 +557,13 @@ func stringSetter(f func(sysVars *systemVariables) *string) setter {
 	}
 }
 
+func boolAccessor(f func(variables *systemVariables) *bool) accessor {
+	return accessor{
+		Setter: boolSetter(f),
+		Getter: boolGetter(f),
+	}
+}
+
 func stringAccessor(f func(variables *systemVariables) *string) accessor {
 	return accessor{
 		Setter: stringSetter(f),