// details responds to an inspection request for a single expression
func details(w http.ResponseWriter, r *http.Request) {
field := fmt.Sprintf("v%d", baseExpr)
expr := r.FormValue(field) // must read before any writing
expr = strings.TrimSpace(expr) // trim leading/trailing blanks
putheader(w, r, "Inspect Expression")
tree, err := rx.Parse(expr)
if err == nil {
fmt.Fprintf(w, "<P>Regular Expression: %s\n", hx(expr))
// must print (or at least stringize) tree before augmenting
fmt.Fprintf(w, "<P>Initial Parse Tree: %s\n", hx(tree))
augt := rx.Augment(tree, 0)
dfa := rx.BuildDFA(augt)
dmin := dfa.Minimize()
fmt.Fprintf(w, "<P>Augmented Tree: %s\n", hx(augt))
fmt.Fprintf(w, "<h2>Examples</h2>\n<P>")
genexamples(w, tree, 0)
genexamples(w, tree, 1)
genexamples(w, tree, 2)
genexamples(w, tree, 3)
genexamples(w, tree, 5)
genexamples(w, tree, 8)
showaut(w, dmin, []string{expr})
} else {
fmt.Fprint(w, "<P>")
showerror(w, err)
}
fmt.Fprint(w, "<h2>Try another?</h2>")
putform(w, "/details", "Enter a regular expression:",
1, []string{expr}, 0, nil)
putfooter(w, r)
}
// multaut displays a multi-NFA and multi-DFA
func multaut(w http.ResponseWriter, r *http.Request) {
// must read all input before writing anything
exprlist := getexprs(r)
nx := len(exprlist)
// parse and echo the input
treelist := make([]rx.Node, 0, nx)
putheader(w, r, "Multi-expression Automata")
fmt.Fprintf(w, "<P class=xleading>%d expressions:\n", nx)
for i, s := range exprlist {
fmt.Fprintf(w, "<BR><B>%c:</B> %s\n",
rx.AcceptLabels[i], hx(s))
tree, err := rx.Parse(s)
if !showerror(w, err) {
treelist = append(treelist, rx.Augment(tree, i))
}
}
if nx > 0 && len(treelist) == nx { // if no errors
dfa := rx.MultiDFA(treelist) // build combined DFA
dmin := dfa.Minimize()
showaut(w, dmin, exprlist)
}
putfooter(w, r)
}
// lpxc -- list and parse expressions for comparison, returning augtree list
func lpxc(w http.ResponseWriter, exprlist []string) []rx.Node {
treelist := make([]rx.Node, 0)
for i, s := range exprlist {
fmt.Fprintf(w,
"<SPAN class=%s><BR><B>%c:</B> %s</SPAN>\n",
colorname(i), rx.AcceptLabels[i], hx(s))
tree, err := rx.Parse(s)
if !showerror(w, err) {
treelist = append(treelist, rx.Augment(tree, i))
}
}
return treelist
}
// draw produces a Dot file for rendering a DFA or NFA in the user's browser.
func draw(w http.ResponseWriter, r *http.Request, which string) {
exprlist := getexprs(r) // must load data before writing anything
nx := len(exprlist)
putheader(w, r, which+" Graph") // write page header
fmt.Fprintln(w, "<P class=xleading>")
treelist := make([]rx.Node, 0)
for i, e := range exprlist {
if nx > 1 {
fmt.Fprintf(w, "%c. ", rx.AcceptLabels[i])
}
fmt.Fprintf(w, "%s<BR>\n", hx(e))
tree, err := rx.Parse(e)
if !showerror(w, err) {
treelist = append(treelist, rx.Augment(tree, i))
}
}
if nx > 0 && len(treelist) == nx { // if no errors
dfa := rx.MultiDFA(treelist) // build combined DFA
dmin := dfa.Minimize() // minimize it
fmt.Fprintln(w, `<script type="text/vnd.graphviz" id="graph">`)
if which == "NFA" {
dmin.GraphNFA(w, "")
} else if nx == 1 {
dmin.ToDot(w, "", "")
} else {
which = "Multi"
dmin.ToDot(w, "", rx.AcceptLabels)
}
fmt.Fprintln(w, `</script>`)
tDraw.Execute(w, which)
}
putfooter(w, r)
}
// refexamine advertises the Examine page
func refexamine(w http.ResponseWriter) {
fmt.Fprint(w, `
<P> On the <A HREF="/examine">Examine</A> page you can enter
a regular expression to generate several kinds of data:
parse trees, synthetic examples, and the automata state lists.
Links from there produce diagrams of either the
<A HREF="http://en.wikipedia.org/wiki/Nondeterministic_finite_automaton">NFA</A>
or
<A HREF="http://en.wikipedia.org/wiki/Deterministic_finite_automaton">DFA</A>
for the language.
`)
tree, _ := rx.Parse(HomeExample)
augt := rx.Augment(tree, 0)
fmt.Fprintf(w, `
<DIV CLASS=inblock>Regular Expression: %s
<BR>Augmented Parse Tree: %s
<BR class=xleading>Examples:<BR>`, hx(HomeExample), hx(augt))
genexamples(w, augt, 0)
genexamples(w, augt, 2)
genexamples(w, augt, 4)
fmt.Fprintln(w, `<DIV class="rside smaller">`)
genexam(w, "submit this example to see full output", HomeExample)
fmt.Fprintln(w, `</DIV></DIV>`)
}
