From e11bcf3d91e613363efa9e9c91d2aeb81faa0c75 Mon Sep 17 00:00:00 2001
From: Jordan Orelli <jorelli@etsy.com>
Date: Sun, 16 Jun 2013 22:23:35 -0400
Subject: [PATCH] added very sloppy tcp functionality

can now send multi-line sexps over TCP.  Max line limit is 40 lines in a
single sexp.  A max needed to be selected to prevent clients from
filling up enormous buffers.
---
 skeam.go           | 16 +++++------
 tcp_connections.go | 67 +++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 71 insertions(+), 12 deletions(-)

diff --git a/skeam.go b/skeam.go
index 650302a..0842d19 100644
--- a/skeam.go
+++ b/skeam.go
@@ -137,27 +137,27 @@ func (s *sexp) readIn(c chan token) error {
 			s.append(v)
 		}
 	}
+	fmt.Println("sexp.readIn hit weird EOF")
 	return errors.New("unexpected EOF in sexp.readIn")
 }
 
 // parses one value that can be evaled from the channel
-func parse(c chan token) (interface{}, bool, error) {
+func parse(c chan token) (interface{}, error) {
 	for t := range c {
 		switch t.t {
 		case closeParenToken:
-			return nil, false, errors.New("unexpected EOF in read")
+			return nil, errors.New("unexpected close paren in read")
 		case openParenToken:
 			s := newSexp()
 			if err := s.readIn(c); err != nil {
-				return nil, true, err
+				return nil, err
 			}
-			return s, false, nil
+			return s, nil
 		default:
-			v, err := atom(t)
-			return v, false, err
+			return atom(t)
 		}
 	}
-	return nil, false, io.EOF
+	return nil, io.EOF
 }
 
 func eval(v interface{}, env *environment) (interface{}, error) {
@@ -210,7 +210,7 @@ func eval(v interface{}, env *environment) (interface{}, error) {
 
 func evalall(c chan token, out chan interface{}, e chan error, env *environment) {
 	for {
-		v, _, err := parse(c)
+		v, err := parse(c)
 		switch err {
 		case io.EOF:
 			return
diff --git a/tcp_connections.go b/tcp_connections.go
index 98e7c50..09413be 100644
--- a/tcp_connections.go
+++ b/tcp_connections.go
@@ -3,14 +3,48 @@ package main
 import (
 	"./cm"
 	"bufio"
+	"errors"
 	"fmt"
 	"io"
 	"net"
+	"strings"
 )
 
+const MAX_SEXP_LINES = 40
+
 var manager = cm.New()
+var errSexpTooLong = errors.New("error: sexp is too long")
+
+func depth(s string) int {
+	n := 0
+	for _, r := range s {
+		switch r {
+		case '(':
+			n += 1
+		case ')':
+			n -= 1
+		}
+	}
+	return n
+}
 
 func tcpInterpreter(conn net.Conn, userinput chan string, out chan interface{}, errors chan error) {
+	lines := make([]string, 0, MAX_SEXP_LINES)
+	currentDepth := 0
+	addLine := func(line string) error {
+		if len(lines) >= MAX_SEXP_LINES {
+			return errSexpTooLong
+		}
+		lines = append(lines, line)
+		return nil
+	}
+	errorMode := false
+	skipLine := func(line string) {
+		currentDepth += depth(line)
+		if currentDepth == 0 {
+			errorMode = false
+		}
+	}
 	for {
 		select {
 		case v := <-out:
@@ -18,10 +52,35 @@ func tcpInterpreter(conn net.Conn, userinput chan string, out chan interface{},
 		case err := <-errors:
 			fmt.Fprintf(conn, "error: %v", err)
 		case line := <-userinput:
-			tokens := make(chan token, 32)
-			// this is probably dumb
-			go lexs(line+"\n", tokens)
-			go evalall(tokens, out, errors, universe)
+			if errorMode {
+				skipLine(line)
+				break
+			}
+			lineDepth := depth(line)
+			currentDepth += lineDepth
+
+			if len(lines) == 0 && lineDepth == 0 {
+				tokens := make(chan token, 32)
+				go lexs(line+"\n", tokens)
+				go evalall(tokens, out, errors, universe)
+				break
+			}
+
+			if err := addLine(line); err != nil {
+				fmt.Fprintf(conn, "error in addLine: %v", err)
+				errorMode = true
+				lines = lines[:0]
+				currentDepth = 0
+				break
+			}
+
+			if currentDepth == 0 {
+				runnable := strings.Join(lines, " ")
+				lines = lines[:0]
+				tokens := make(chan token, 32)
+				go lexs(runnable+"\n", tokens)
+				go evalall(tokens, out, errors, universe)
+			}
 		}
 	}
 }