add Zed url_parse function

expr/function/function.go

@@ -3,6 +3,8 @@ package function
 import (
 	"errors"
 	"fmt"
+	"net/url"
+	"strconv"
 	"strings"
 
 	"github.com/brimdata/zed/anymath"
@@ -113,6 +115,8 @@ func New(zctx *zson.Context, name string, narg int) (Interface, bool, error) {
 	case "network_of":
 		argmax = 2
 		f = &networkOf{}
+	case "url_parse":
+		f = &urlParse{marshaler: zson.NewZNGMarshalerWithContext(zctx)}
 	case "zson_parse":
 		f = &zsonParse{zctx: zctx}
 	}
@@ -233,6 +237,72 @@ func (i *is) Call(args []zng.Value) (zng.Value, error) {
 	return zng.False, nil
 }
 
+type urlParse struct {
+	marshaler *zson.MarshalZNGContext
+}
+
+func (u *urlParse) Call(args []zng.Value) (zng.Value, error) {
+	in := args[0]
+	if !in.IsStringy() {
+		return badarg("url_parse: input must be string")
+	}
+	if in.Bytes == nil {
+		return badarg("url_parse: input must not be null")
+	}
+	s, err := zng.DecodeString(in.Bytes)
+	if err != nil {
+		return zng.Value{}, err
+	}
+	ur, err := url.Parse(s)
+	if err != nil {
+		return zng.Value{}, fmt.Errorf("url_parse: %q: %w", s, errors.Unwrap(err))
+	}
+	var v struct {
+		Scheme   *string    `zng:"scheme"`
+		Opaque   *string    `zng:"opaque"`
+		User     *string    `zng:"user"`
+		Password *string    `zng:"password"`
+		Host     *string    `zng:"host"`
+		Port     *uint16    `zng:"port"`
+		Path     *string    `zng:"path"`
+		Query    url.Values `zng:"query"`
+		Fragment *string    `zng:"fragment"`
+	}
+	if ur.Scheme != "" {
+		v.Scheme = &ur.Scheme
+	}
+	if ur.Opaque != "" {
+		v.Opaque = &ur.Opaque
+	}
+	if s := ur.User.Username(); s != "" {
+		v.User = &s
+	}
+	if s, ok := ur.User.Password(); ok {
+		v.Password = &s
+	}
+	if s := ur.Hostname(); s != "" {
+		v.Host = &s
+	}
+	if ss := ur.Port(); ss != "" {
+		u64, err := strconv.ParseUint(ss, 10, 16)
+		if err != nil {
+			return zng.Value{}, fmt.Errorf("url_parse: %q: invalid port: %s", s, errors.Unwrap(err))
+		}
+		u16 := uint16(u64)
+		v.Port = &u16
+	}
+	if ur.Path != "" {
+		v.Path = &ur.Path
+	}
+	if q := ur.Query(); len(q) > 0 {
+		v.Query = q
+	}
+	if ur.Fragment != "" {
+		v.Fragment = &ur.Fragment
+	}
+	return u.marshaler.Marshal(v)
+}
+
 type zsonParse struct {
 	zctx *zson.Context
 }

expr/ztests/url-parse.yaml

@@ -0,0 +1,86 @@
+zed: |
+  url := url_parse(s)
+
+input: |
+  {s:""}
+  {s:"scheme://user:password@host:12345/path?a=1&a=2&b=3&c=#fragment"}
+  {s:"scheme:opaque"}
+  {s:1}
+  {s:null(string)}
+  {s:":no-scheme"}
+  {s:"scheme://bad-port:1234567"}
+
+output-flags: -pretty=2
+
+output: |
+  {
+    s: "",
+    url: {
+      scheme: null (string),
+      opaque: null (string),
+      user: null (string),
+      password: null (string),
+      host: null (string),
+      port: null (uint16),
+      path: null (string),
+      query: null (|{string,[string]}|),
+      fragment: null (string)
+    }
+  }
+  {
+    s: "scheme://user:password@host:12345/path?a=1&a=2&b=3&c=#fragment",
+    url: {
+      scheme: "scheme",
+      opaque: null (string),
+      user: "user",
+      password: "password",
+      host: "host",
+      port: 12345 (uint16),
+      path: "/path",
+      query: |{
+        {"a",[
+            "1",
+            "2"
+          ]},
+        {"b",[
+            "3"
+          ]},
+        {"c",[
+            ""
+          ]}
+      }|,
+      fragment: "fragment"
+    }
+  }
+  {
+    s: "scheme:opaque",
+    url: {
+      scheme: "scheme",
+      opaque: "opaque",
+      user: null (string),
+      password: null (string),
+      host: null (string),
+      port: null (uint16),
+      path: null (string),
+      query: null (|{string,[string]}|),
+      fragment: null (string)
+    }
+  }
+  {
+    s: 1
+  }
+  {
+    s: null (string)
+  }
+  {
+    s: ":no-scheme"
+  }
+  {
+    s: "scheme://bad-port:1234567"
+  }
+
+warnings: |
+  url_parse: input must be string: bad argument
+  url_parse: input must not be null: bad argument
+  url_parse: ":no-scheme": missing protocol scheme
+  url_parse: "scheme://bad-port:1234567": invalid port: value out of range