#1: Add HandleScreen() function as a higher-level interface to ShowScreen()
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Matthew R. Wilson committed
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@@ -1,3 +1,3 @@
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*.exe
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example/example
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example1/example1
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example2/example2
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File renamed without changes.
@@ -0,0 +1,155 @@
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// This file is part of https://github.com/racingmars/go3270/
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// Copyright 2020 by Matthew R. Wilson, licensed under the MIT license. See
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// LICENSE in the project root for license information.
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package main
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import (
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"fmt"
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"net"
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"os"
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"strings"
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"github.com/racingmars/go3270"
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)
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func init() {
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// put the go3270 library in debug mode
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go3270.Debug = os.Stderr
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}
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// A Screen is an array of go3270.Field structs. We will build two screens,
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// a query screen and a result screen:
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var screen1 = go3270.Screen{
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{Row: 0, Col: 27, Intense: true, Content: "3270 Example Application"},
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{Row: 2, Col: 0, Content: "Welcome to the go3270 example application. Please enter your name."},
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{Row: 4, Col: 0, Content: "First Name . . ."},
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{Row: 4, Col: 19, Name: "fname", Write: true, Highlighting: go3270.Underscore},
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{Row: 4, Col: 40}, // field "stop" character
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{Row: 5, Col: 0, Content: "Last Name . . . ."},
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{Row: 5, Col: 19, Name: "lname", Write: true, Highlighting: go3270.Underscore},
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{Row: 5, Col: 40}, // field "stop" character,
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{Row: 6, Col: 0, Content: "Password . . . ."},
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{Row: 6, Col: 19, Name: "password", Write: true, Hidden: true},
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{Row: 6, Col: 40}, // field "stop" character,
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{Row: 7, Col: 0, Content: "Change me . . ."},
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{Row: 7, Col: 19, Name: "changeme", Content: "change me", Write: true, Highlighting: go3270.Underscore},
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{Row: 7, Col: 40}, // field "stop" character
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{Row: 8, Col: 0, Content: "Press"},
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{Row: 8, Col: 6, Intense: true, Content: "enter"},
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{Row: 8, Col: 12, Content: "to submit your name."},
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{Row: 10, Col: 0, Intense: true, Color: go3270.Red, Name: "errormsg"}, // a blank field for error messages
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{Row: 22, Col: 0, Content: "PF3 Exit"},
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}
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var screen1rules = go3270.Rules{
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"fname": {Validator: go3270.NonBlank},
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"lname": {Validator: go3270.NonBlank},
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"password": {Validator: go3270.NonBlank, Reset: true},
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"changeme": {Validator: go3270.NonBlank, MustChange: true, ErrorText: "You can't leave \"change me\" as the value in the Change me field"},
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}
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var screen2 = go3270.Screen{
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{Row: 0, Col: 27, Intense: true, Content: "3270 Example Application"},
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{Row: 2, Col: 0, Content: "Thank you for submitting your name. Here's what I know:"},
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{Row: 4, Col: 0, Content: "Your first name is"},
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{Row: 4, Col: 19, Name: "fname"}, // We're giving this field a name to replace its value at runtime
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{Row: 5, Col: 0, Content: "And your last name is"},
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{Row: 5, Col: 22, Name: "lname"}, // We're giving this field a name to replace its value at runtime
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{Row: 6, Col: 0, Name: "passwordOutput"},
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{Row: 8, Col: 0, Content: "Press"},
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{Row: 8, Col: 6, Intense: true, Content: "enter"},
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{Row: 8, Col: 12, Content: "to enter your name again, or"},
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{Row: 8, Col: 41, Intense: true, Content: "PF3"},
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{Row: 8, Col: 45, Content: "to quit and disconnect."},
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{Row: 11, Col: 0, Color: go3270.Turquoise, Highlighting: go3270.ReverseVideo, Content: "Here is a field with extended attributes."},
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{Row: 11, Col: 42}, // remember to "stop" fields with a regular field, to clear the reverse video for example
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{Row: 20, Col: 0, Intense: true, Color: go3270.Red, Name: "errormsg"}, // a blank field for error messages
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{Row: 22, Col: 0, Content: "PF3 Exit"},
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}
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func main() {
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ln, err := net.Listen("tcp", ":3270")
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if err != nil {
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panic(err)
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}
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fmt.Println("LISTENING ON PORT 3270 FOR CONNECTIONS")
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fmt.Println("Press Ctrl-C to end server.")
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for {
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conn, err := ln.Accept()
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if err != nil {
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panic(err)
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}
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go handle(conn)
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}
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}
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// handle is the handler for individual user connections.
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func handle(conn net.Conn) {
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defer conn.Close()
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// Always begin new connection by negotiating the telnet options
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go3270.NegotiateTelnet(conn)
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fieldValues := make(map[string]string)
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// We will loop forever until the user quits
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for {
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// First we display screen 1. The HandleScreen() function handles
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// input validation and processing attention keys we don't handle.
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response, err := go3270.HandleScreen(
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screen1, // the screen to display
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screen1rules, // the rules to enforce
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fieldValues, // any field values we wish to supply
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[]go3270.AID{go3270.AIDEnter}, // the AID keys we support
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[]go3270.AID{go3270.AIDPF3}, // keys that are "exit" keys
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"errormsg", // the field to write error message into
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4, 20, // the row and column to place the cursor
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conn)
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if err != nil {
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fmt.Println(err)
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return
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}
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if response.AID == go3270.AIDPF3 {
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// Exit
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break
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}
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fieldValues = response.Values
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// Now we're ready to display screen2
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passwordLength := len(strings.TrimSpace(fieldValues["password"]))
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passwordPlural := "s"
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if passwordLength == 1 {
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passwordPlural = ""
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}
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fieldValues["passwordOutput"] = fmt.Sprintf("Your password was %d character%s long",
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passwordLength, passwordPlural)
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response, err = go3270.HandleScreen(
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screen2, // the screen to display
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nil, // the rules to enforce
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fieldValues, // any field values we wish to supply
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[]go3270.AID{go3270.AIDEnter}, // the AID keys we support
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[]go3270.AID{go3270.AIDPF3}, // keys that are "exit" keys
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"errormsg", // the field to write error message into
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0, 0, // the row and column to place the cursor
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conn)
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if err != nil {
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fmt.Println(err)
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return
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}
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// If the user pressed PF3, exit
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if response.AID == go3270.AIDPF3 {
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break
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}
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// If they pressed anything else, just let the loop continue...
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continue
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}
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fmt.Println("Connection closed")
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}
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@@ -0,0 +1,209 @@
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// This file is part of https://github.com/racingmars/go3270/
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// Copyright 2020 by Matthew R. Wilson, licensed under the MIT license. See
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// LICENSE in the project root for license information.
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package go3270
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import (
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"fmt"
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"net"
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"regexp"
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"strings"
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)
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// Rules is a map of field names (strings) to FieldRules structs. Each field
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// for which you wish validation to occur must appear in the map. Fields not
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// in the map will not have any input validation performed.
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type Rules map[string]FieldRules
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// Validator is a type that represents a function which can perform field
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// input validation. The function is passed a string, input, and returns
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// true if the input is valid or false if the not.
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type Validator func(input string) bool
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// NonBlank is a Validator that returns true if, after spaces are trimmed from
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// the beginning and end of the string, the value is not empty.
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var NonBlank Validator = func(input string) bool {
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return !(strings.TrimSpace(input) == "")
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}
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var isIntegerRegexp = regexp.MustCompile(`^-?[0-9]+$`)
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// IsInteger is a Validator that returns true if, after spaces are trimmed from
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// the beginning and end if the string, the value is an integer (including
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// negative numbers and 0).
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var IsInteger Validator = func(input string) bool {
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input = strings.TrimSpace(input)
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return isIntegerRegexp.MatchString(input)
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}
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// FieldRules provides the validation rules for a particular field.
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type FieldRules struct {
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// MustChange, when true, indicates that the value of the field MUST be
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// altered by the user -- if applied to a field with no starting value,
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// this makes the field a required field. If true on a field with a
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// starting value (either in the field's Content attribute, or with an
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// override in the initial values map), then the user must change
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// the value from the default.
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MustChange bool
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// ErrorText is the text displayed with the MustChange validation fails.
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// If ErrorText is the empty string, but MustValidation fails, an error
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// string will be constructed from the field name: "Please enter a valid
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// value for <fieldName>."
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ErrorText string
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// Validator is a function to validate the value the user input into the
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// field. It may be nil if no validation is required. The Validator
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// function is called *after* the MustChange logic, so if you wish to
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// fully handle validation, ensure MustChange is set to false.
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Validator Validator
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// Reset indicates that if the screen fails validation, this field should
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// always be reset to its original/default value, regardless of what the
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// user entered.
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Reset bool
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}
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// HandleScreen is a higher-level interface to the ShowScreen() function.
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// HandleScreen will loop until all validation rules are satisfied, and only
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// return when an expected AID (i.e. PF) key is pressed.
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//
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// - screen is the Screen to display (see ShowScreen()).
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// - rules are the Rules to enforce: each key in the Rules map corresponds to
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// a Field.Name in the screen array.
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// - values are field values you wish to override (see ShowScreen()).
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// - pfkeys and exitkeys are the AID keys that you wish to accept (that is,
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// perform validation and return if successful) and treat as exit keys
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// (unconditionally return).
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// - errorField is the name of a field in the screen array that you wish error
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// messages to be written in when HandleScreen loops waiting for a valid
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// user submission.
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// - crow and ccol are the initial cursor position.
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// - conn is the network connection to the 3270 client.
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//
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// HandleScreen will return when the user: 1) presses a key in pfkeys AND all
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// fields pass validation, OR 2) the user presses a key in exitkeys. In all
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// other cases, HandleScreen will re-present the screen to the user again,
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// possibly with an error message set in the errorField field.
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func HandleScreen(screen Screen, rules Rules, values map[string]string,
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pfkeys, exitkeys []AID, errorField string, crow, ccol int,
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conn net.Conn) (Response, error) {
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// Save the original field values for any named fields to support
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// the MustChange rule. Also build a map of named fields.
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origValues := make(map[string]string)
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fields := make(map[string]*Field)
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for i := range screen {
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if screen[i].Name != "" {
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origValues[screen[i].Name] = screen[i].Content
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fields[screen[i].Name] = &screen[i]
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}
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}
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// Make our own field values map so we don't alter the caller's values
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myValues := make(map[string]string)
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for field := range values {
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myValues[field] = values[field]
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}
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// Now we loop...
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mainloop:
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for {
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// Reset fields with FieldRules.Reset set
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for field := range rules {
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if rules[field].Reset {
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// avoid problems if there is a rule for a non-existent field
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if _, ok := fields[field]; ok {
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// Is the value in the origValues map?
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if value, ok := origValues[field]; ok {
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myValues[field] = value
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} else {
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// remove from the values map so we fall back to
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// whatever default is set for the field
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delete(myValues, field)
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}
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}
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}
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}
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resp, err := ShowScreen(screen, myValues, crow, ccol, conn)
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if err != nil {
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return resp, err
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}
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// If we got an exit key, return without performing validation
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if aidInArray(resp.AID, exitkeys) {
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return resp, nil
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}
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// If we got an unexpected key, set error message and restart loop
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if !aidInArray(resp.AID, pfkeys) {
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if !(resp.AID == AIDClear || resp.AID == AIDPA1 || resp.AID == AIDPA2 ||
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resp.AID == AIDPA3) {
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myValues = mergeFieldValues(myValues, resp.Values)
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}
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myValues[errorField] = fmt.Sprintf("%s: unknown key",
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AIDtoString(resp.AID))
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continue
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}
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// At this point, we have an expected key. If one of the "clear" keys
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// is expected, we can't do much, so we'll just return.
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if resp.AID == AIDClear || resp.AID == AIDPA1 || resp.AID == AIDPA2 ||
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resp.AID == AIDPA3 {
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return resp, nil
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}
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myValues = mergeFieldValues(myValues, resp.Values)
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delete(myValues, errorField) // don't persist errors across refreshes
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// Now we can validate each field
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for field := range rules {
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// skip rules for fields that don't exist
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if _, ok := myValues[field]; !ok {
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continue
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}
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if rules[field].MustChange && myValues[field] == origValues[field] {
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myValues[errorField] = rules[field].ErrorText
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continue mainloop
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}
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if rules[field].Validator != nil && !rules[field].Validator(myValues[field]) {
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myValues[errorField] = fmt.Sprintf("Value for %s is not valid", field)
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continue mainloop
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}
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}
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// Everything passed validation
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return resp, nil
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}
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}
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// aidInArray performs a linear search through the aids array and returns true
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// if aid appears in the array, false otherwise.
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func aidInArray(aid AID, aids []AID) bool {
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for i := range aids {
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if aids[i] == aid {
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return true
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}
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}
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return false
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}
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// mergeFieldValues will return a new map, containing all keys from the current
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// map and keys from the original map that do not exist in the current map.
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// This is sometimes necessary because the caller of HandleScreen() may
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// provide override values for non-writable fields, and we don't get those
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// values back when we round-trip with the 3270 client.
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func mergeFieldValues(original, current map[string]string) map[string]string {
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result := make(map[string]string)
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for key := range current {
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result[key] = current[key]
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}
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for key := range original {
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if _, ok := result[key]; !ok {
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result[key] = original[key]
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}
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}
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return result
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}
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@@ -48,3 +48,71 @@ var decodes = []int{-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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23, 24, 25, -1, -1, -1, -1, -1, -1, -1, -1, 34, 35, 36, 37, 38, 39, 40,
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41, -1, -1, -1, -1, -1, -1, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, -1,
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-1, -1, -1, -1}
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// AIDtoString returns a string representation of an AID key name.
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func AIDtoString(aid AID) string {
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switch aid {
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case AIDClear:
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return "Clear"
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case AIDEnter:
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return "Enter"
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case AIDNone:
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return "[none]"
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case AIDPA1:
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return "PA1"
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case AIDPA2:
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return "PA2"
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case AIDPA3:
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return "PA3"
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case AIDPF1:
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return "PF1"
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case AIDPF2:
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return "PF2"
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case AIDPF3:
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return "PF3"
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case AIDPF4:
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return "PF4"
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case AIDPF5:
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return "PF5"
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case AIDPF6:
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return "PF6"
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case AIDPF7:
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return "PF7"
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case AIDPF8:
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return "PF8"
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case AIDPF9:
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return "PF9"
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case AIDPF10:
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return "PF10"
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case AIDPF11:
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return "PF11"
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case AIDPF12:
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return "PF12"
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case AIDPF13:
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return "PF13"
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case AIDPF14:
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return "PF14"
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case AIDPF15:
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return "PF15"
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case AIDPF16:
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return "PF16"
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case AIDPF17:
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return "PF17"
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case AIDPF18:
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return "PF18"
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case AIDPF19:
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return "PF19"
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case AIDPF20:
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return "PF20"
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case AIDPF21:
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return "PF21"
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case AIDPF22:
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return "PF22"
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case AIDPF23:
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return "PF23"
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case AIDPF24:
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return "PF24"
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default:
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return "[unknown]"
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}
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}
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Reference in new issue
Block a user