Add support for python reducers

pkg/reducer/nodejs.go

@@ -0,0 +1,93 @@
+package reducer
+
+import (
+	_ "embed"
+	"fmt"
+	"os"
+	"os/exec"
+	"regexp"
+	"strings"
+)
+
+func CreateNodejs(args []string) *exec.Cmd {
+	cmd := exec.Command("node", "-e", GenerateCode(args))
+	cmd.Env = os.Environ()
+	cmd.Env = append(cmd.Env, "NODE_OPTIONS=--max-old-space-size=8192")
+	return cmd
+}
+
+//go:embed reduce.js
+var templateJs string
+
+func GenerateCodeNodejs(args []string) string {
+	rs := "\n"
+	for i, a := range args {
+		rs += "  try {"
+		switch {
+		case a == ".":
+			rs += `
+    x = function () 
+      { return this }
+    .call(x)
+`
+
+		case flatMapRegex.MatchString(a):
+			code := fold(strings.Split(a, "[]"))
+			rs += fmt.Sprintf(
+				`
+    x = (
+      %v
+    )(x)
+`, code)
+
+		case strings.HasPrefix(a, ".["):
+			rs += fmt.Sprintf(
+				`
+    x = function () 
+      { return this%v } 
+    .call(x)
+`, a[1:])
+
+		case strings.HasPrefix(a, "."):
+			rs += fmt.Sprintf(
+				`
+    x = function () 
+      { return this%v } 
+    .call(x)
+`, a)
+
+		default:
+			rs += fmt.Sprintf(
+				`
+    f = function () 
+      { return %v }
+    .call(x)
+    x = typeof f === 'function' ? f(x) : fn
+`, a)
+		}
+		// Generate a beautiful error message.
+		rs += "  } catch (e) {\n"
+		pre, post, pointer := trace(args, i)
+		rs += fmt.Sprintf(
+			"    throw `\\n  ${%q} ${%q} ${%q}\\n  %v\\n\\n${e.stack || e}`\n",
+			pre, a, post, pointer,
+		)
+		rs += "  }\n"
+	}
+	return fmt.Sprintf(templateJs, rs)
+}
+
+var flatMapRegex = regexp.MustCompile("^(\\.\\w*)+\\[]")
+
+func fold(s []string) string {
+	if len(s) == 1 {
+		return "x => x" + s[0]
+	}
+	obj := s[0]
+	if obj == "." {
+		obj = "x"
+	} else {
+		obj = "x" + obj
+	}
+	return fmt.Sprintf("x => Object.values(%v).flatMap(%v)", obj, fold(s[1:]))
+}

pkg/reducer/python.go

@@ -0,0 +1,46 @@
+package reducer
+
+import (
+	_ "embed"
+	"fmt"
+	"os/exec"
+)
+
+func CreatePython(bin string, args []string) *exec.Cmd {
+	cmd := exec.Command(bin, "-c", GenerateCode(args))
+	return cmd
+}
+
+//go:embed reduce.py
+var templatePython string
+
+func GenerateCodePython(args []string) string {
+	rs := "\n"
+	for i, a := range args {
+		rs += "try:"
+		switch {
+		case a == ".":
+			rs += `
+    x = x
+`
+
+		default:
+			rs += fmt.Sprintf(
+				`
+    f = (lambda json: (%v))(x)
+    x = f(x) if callable(f) else f
+`, a)
+		}
+		// Generate a beautiful error message.
+		rs += "except Exception as e:\n"
+		pre, post, pointer := trace(args, i)
+		rs += fmt.Sprintf(
+			`    sys.stderr.write('\n  {} {} {}\n  %v\n\n{}\n'.format(%q, %q, %q, e))
+    sys.exit(1)`,
+			pointer,
+			pre, a, post,
+		)
+		rs += "\n"
+	}
+	return fmt.Sprintf(templatePython, rs)
+}

pkg/reducer/reduce.go

@@ -5,112 +5,45 @@ import (
 	_ "embed"
 	"encoding/json"
 	"fmt"
-	. "github.com/antonmedv/fx/pkg/json"
-	. "github.com/antonmedv/fx/pkg/theme"
 	"os"
 	"os/exec"
-	"regexp"
 	"strings"
-)
 
-//go:embed reduce.js
+	. "github.com/antonmedv/fx/pkg/json"
-var template string
+	. "github.com/antonmedv/fx/pkg/theme"
-
+)
-var flatMapRegex = regexp.MustCompile("^(\\.\\w*)+\\[]")
 
 func GenerateCode(args []string) string {
-	rs := "\n"
+	lang, ok := os.LookupEnv("FX_LANG")
-	for i, a := range args {
+	if !ok {
-		rs += "  try {"
+		lang = "node"
-		switch {
+	}
-		case a == ".":
+	switch {
-			rs += `
+	case lang == "node":
-    json = function () 
+		return GenerateCodeNodejs(args)
-      { return this }
+	case strings.HasPrefix(lang, "python"):
-    .call(json)
+		return GenerateCodePython(args)
-`
+	default:
-
+		panic("unknown lang")
-		case flatMapRegex.MatchString(a):
-			code := fold(strings.Split(a, "[]"))
-			rs += fmt.Sprintf(
-				`
-    json = (
-      %v
-    )(json)
-`, code)
-
-		case strings.HasPrefix(a, ".["):
-			rs += fmt.Sprintf(
-				`
-    json = function () 
-      { return this%v } 
-    .call(json)
-`, a[1:])
-
-		case strings.HasPrefix(a, "."):
-			rs += fmt.Sprintf(
-				`
-    json = function () 
-      { return this%v } 
-    .call(json)
-`, a)
-
-		default:
-			rs += fmt.Sprintf(
-				`
-    fn = function () 
-      { return %v }
-    .call(json)
-    json = typeof fn === 'function' ? json = fn(json) : fn
-`, a)
-		}
-		// Generate a beautiful error message.
-		rs += "  } catch (e) {\n"
-		pre := strings.Join(args[:i], " ")
-		if len(pre) > 20 {
-			pre = "..." + pre[len(pre)-20:]
-		}
-		post := strings.Join(args[i+1:], " ")
-		if len(post) > 20 {
-			post = post[:20] + "..."
-		}
-		pointer := fmt.Sprintf(
-			"%v %v %v",
-			strings.Repeat(" ", len(pre)),
-			strings.Repeat("^", len(a)),
-			strings.Repeat(" ", len(post)),
-		)
-		rs += fmt.Sprintf(
-			"    throw `\\n"+
-				"  ${%q} ${%q} ${%q}\\n"+
-				"  %v\\n"+
-				"\\n${e.stack || e}`\n",
-			pre, a, post,
-			pointer,
-		)
-		rs += "  }\n"
 	}
-	return fmt.Sprintf(template, rs)
 }
 
-func fold(s []string) string {
+func Reduce(object interface{}, args []string, theme Theme) {
-	if len(s) == 1 {
+	var cmd *exec.Cmd
-		return "x => x" + s[0]
+	lang, ok := os.LookupEnv("FX_LANG")
+	if !ok {
+		lang = "node"
 	}
-	obj := s[0]
+	switch {
-	if obj == "." {
+	case lang == "node":
-		obj = "x"
+		cmd = CreateNodejs(args)
-	} else {
+	case strings.HasPrefix(lang, "python"):
-		obj = "x" + obj
+		cmd = CreatePython(lang, args)
+	default:
+		panic("unknown lang")
 	}
-	return fmt.Sprintf("x => Object.values(%v).flatMap(%v)", obj, fold(s[1:]))
-}
 
-func Reduce(object interface{}, args []string, theme Theme) {
 	var stdout, stderr bytes.Buffer
-	cmd := exec.Command("node", "-e", GenerateCode(args))
-	cmd.Env = os.Environ()
-	cmd.Env = append(cmd.Env, "NODE_OPTIONS=--max-old-space-size=8192")
 	cmd.Stdin = strings.NewReader(Stringify(object))
 	cmd.Stdout = &stdout
 	cmd.Stderr = &stderr
@@ -138,3 +71,21 @@ func Reduce(object interface{}, args []string, theme Theme) {
 		os.Exit(exitCode)
 	}
 }
+
+func trace(args []string, i int) (pre, post, pointer string) {
+	pre = strings.Join(args[:i], " ")
+	if len(pre) > 20 {
+		pre = "..." + pre[len(pre)-20:]
+	}
+	post = strings.Join(args[i+1:], " ")
+	if len(post) > 20 {
+		post = post[:20] + "..."
+	}
+	pointer = fmt.Sprintf(
+		"%v %v %v",
+		strings.Repeat(" ", len(pre)),
+		strings.Repeat("^", len(args[i])),
+		strings.Repeat(" ", len(post)),
+	)
+	return
+}

pkg/reducer/reduce.js

@@ -14,14 +14,14 @@ void async function () {
   for await (let chunk of process.stdin) {
     buffer += chunk
   }
-  let json = JSON.parse(buffer)
+  let x = JSON.parse(buffer)
 
   // Reducers %v
 
-  if (typeof json === 'undefined') {
+  if (typeof x === 'undefined') {
     process.stderr.write('undefined')
   } else {
-    process.stdout.write(JSON.stringify(json))
+    process.stdout.write(JSON.stringify(x))
   }
 }().catch(err => {
   console.error(err)

pkg/reducer/reduce.py

@@ -0,0 +1,9 @@
+import json, sys, os
+x = json.load(sys.stdin)
+
+# Reducers %v
+
+try:
+    print(json.dumps(x))
+except:
+    print(json.dumps(list(x)))