// combos responds to a comparison request for multiple expressions
func combos(w http.ResponseWriter, r *http.Request) {
// must read all input before writing anything
// first get the expressions, trimming leading/trailing blanks
exprlist := getexprs(r)
nx := len(exprlist)
// then get the test strings; these are not trimmed
testlist := make([]string, 0)
for i := 0; i < maxTest; i++ {
arg := r.FormValue(fmt.Sprintf("v%d", baseTest+i))
if arg != "" {
testlist = append(testlist, arg)
}
}
// parse and echo the input
putheader(w, r, "Compare Expressions")
fmt.Fprintf(w, "<P class=xleading>%d expressions:\n", nx)
treelist := lpxc(w, exprlist)
if nx > 0 && len(treelist) == nx { // if no errors
dfa := rx.MultiDFA(treelist) // build combined DFA
trylist := make([]string, 0) // list of strings to try
// tests from form submission
for _, x := range testlist {
trylist = append(trylist, x)
}
trylist = append(trylist, DRAWLINE)
// examples from DFA
synthx := dfa.Synthesize() // synthesize from DFA
for _, x := range synthx { // put results on list
trylist = append(trylist, x.Example)
}
// DON'T separate parse tree examples
// (confusing in the the absence of a published explanation)
// trylist = append(trylist, DRAWLINE)
// examples from parse tree
for i := 0; i < nx; i++ {
trylist = append(trylist, rx.Specimen(treelist[i], 1))
trylist = append(trylist, rx.Specimen(treelist[i], 2))
trylist = append(trylist, rx.Specimen(treelist[i], 3))
trylist = append(trylist, rx.Specimen(treelist[i], 5))
}
fmt.Fprintf(w, "<H2>Results</H2>\n")
showgrid(w, dfa, nx, trylist) // show examples
}
fmt.Fprintln(w, "<P> ")
formlink(w, "/multaut", exprlist, "Show automata states")
formlink(w, "/drawNFA", exprlist, "Draw the NFA")
formlink(w, "/drawDFA", exprlist, "Draw the DFA")
fmt.Fprint(w, "<h2>Try again?</h2>")
putform(w, "/combos", "Enter regular expressions:",
nExpr, exprlist, nTest, testlist)
putfooter(w, r)
}
// generate examples from a parse tree
func genex(tree rx.Node) []string {
x := make([]string, 0)
for i := 0; i < nexamples; i++ {
r := maxrepl - i%maxrepl
x = append(x, rx.Specimen(tree, r))
}
return x
}
// genexamples writes a line of specimen strings matching the expression
func genexamples(w http.ResponseWriter, tree rx.Node, maxrepl int) {
nprinted := 0
ncolm := 0
for {
s := rx.Specimen(tree, maxrepl)
t := rx.Protect(s)
ncolm += 2 + len(t)
if nprinted > 0 && ncolm > linemax {
break
}
fmt.Fprintf(w, " %s ", hx(t))
nprinted++
}
fmt.Fprint(w, "<BR>\n")
}
// examples generates a line's worth of examples with max replication n.
// Each example is also tested against the DFA.
func examples(dfa *rx.DFA, tree rx.Node, n int) {
s := fmt.Sprintf("ex(%d):", n)
nprinted := 0
fmt.Print(s)
ncolm := utf8.RuneCountInString(s)
for {
s := rx.Specimen(tree, n)
t := rx.Protect(s)
ncolm += 2 + utf8.RuneCountInString(t)
if nprinted > 0 && ncolm > linemax {
break
}
fmt.Printf(" %s", t)
if dfa.Accepts(s) == nil {
fmt.Print(" [FAIL]")
ncolm += 7
}
nprinted++
}
fmt.Println()
}