Add reduce

reduce.go

@@ -0,0 +1,138 @@
+package main
+
+import (
+	"bytes"
+	_ "embed"
+	"encoding/json"
+	"fmt"
+	"os"
+	"os/exec"
+	"regexp"
+	"strings"
+)
+
+//go:embed reduce.js
+var template string
+
+var flatMapRegex = regexp.MustCompile("^(\\.\\w*)+\\[]")
+
+func generateCode(args []string) string {
+	rs := "\n"
+	for i, a := range args {
+		rs += "  try {"
+		switch {
+		case a == ".":
+			rs += `
+    json = function () 
+      { return this }
+    .call(json)
+`
+
+		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(" ", width(pre)),
+			strings.Repeat("^", width(a)),
+			strings.Repeat(" ", width(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 {
+	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:]))
+}
+
+func reduce(object interface{}, args []string) {
+	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
+	err := cmd.Run()
+	if err == nil {
+		dec := json.NewDecoder(&stdout)
+		dec.UseNumber()
+		jsonObject, err := parse(dec)
+		if err == nil {
+			if str, ok := jsonObject.(string); ok {
+				fmt.Println(str)
+			} else {
+				fmt.Println(prettyPrint(jsonObject, 1))
+			}
+		} else {
+			_, _ = fmt.Fprint(os.Stderr, stderr.String())
+		}
+	} else {
+		exitCode := 1
+		status, ok := err.(*exec.ExitError)
+		if ok {
+			exitCode = status.ExitCode()
+		}
+		_, _ = fmt.Fprint(os.Stderr, stderr.String())
+		os.Exit(exitCode)
+	}
+}

reduce.js

@@ -0,0 +1,29 @@
+const os = require('os')
+const fs = require('fs')
+const path = require('path')
+
+try {
+  require(path.join(os.homedir(), '.fxrc'))
+} catch (err) {
+  if (err.code !== 'MODULE_NOT_FOUND') throw err
+}
+
+void async function () {
+  let buffer = ''
+  process.stdin.setEncoding('utf8')
+  for await (let chunk of process.stdin) {
+    buffer += chunk
+  }
+  let json = JSON.parse(buffer)
+
+  // Reducers %v
+
+  if (typeof json === 'undefined') {
+    process.stderr.write('undefined')
+  } else {
+    process.stdout.write(JSON.stringify(json))
+  }
+}().catch(err => {
+  console.error(err)
+  process.exitCode = 1
+})