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parse.go
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parse.go
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package main
import (
"fmt"
"strings"
)
type Quit struct{}
type List struct{}
type Vis struct {
args []string
}
type Help struct{}
func Parse(src string) (interface{}, error) {
if len(src) == 0 {
return nil, nil
} else if len(src) >= 2 && src[:2] == "?=" {
in := strings.Join(strings.Fields(src[2:]), "")
return parseOSQuery(in)
} else if src[0] == '=' || src[0] == '?' {
in := strings.Join(strings.Fields(src), "")
return parseUnop(in)
} else if idx := strings.Index(src, "=>"); idx != -1 {
if idx == 0 {
err := "left handside of rule `%s` is empty"
return nil, fmt.Errorf("error: "+err, src)
} else if len(src) == idx+2 {
err := "right handside of rule `%s` is empty"
return nil, fmt.Errorf("error: "+err, src)
}
lhs := strings.Join(strings.Fields(src[:idx]), "")
rhs := strings.Join(strings.Fields(src[idx+2:]), "")
return parseRule(src, lhs, rhs)
} else if src == "v" || src == "verbose" {
verbose = verbose != true
fmt.Println("verbose =", verbose)
} else if src == "q" || src == "quit" {
return Quit{}, nil
} else if src == "l" || src == "ls" || src == "list" {
return List{}, nil
} else if len(src) >= len("vis") && src[:3] == "vis" {
in := strings.Fields(src)
if len(in) > 1 {
return Vis{args: in[1:]}, nil
}
return Vis{args: nil}, nil
} else if src == "h" || src == "help" {
return Help{}, nil
} else {
split := strings.Fields(src)
if len(split) > 0 && (split[0] == "reset" || split[0] == "r") {
return parseReset(split)
}
err := "unknown expression `%s`"
return nil, fmt.Errorf("error: "+err, src)
}
return nil, nil
}
type Reset struct {
args []byte
}
func parseReset(args []string) (Reset, error) {
out := Reset{}
if len(args) == 1 {
for c := 'A'; c <= 'Z'; c += 1 {
out.args = append(out.args, byte(c))
}
} else {
for _, s := range args[1:] {
if len(s) == 1 {
c := byte(s[0])
if c >= 'A' && c <= 'Z' {
out.args = append(out.args, c)
} else {
err := "unknown literal `%s` in reset"
return out, fmt.Errorf("error: "+err, s)
}
} else {
err := "unknown literal `%s` in reset"
return out, fmt.Errorf("error: "+err, s)
}
}
}
return out, nil
}
// @unop
func parseUnop(op string) (interface{}, error) {
switch op[0] {
case '=':
return assign(op)
case '?':
return query(op)
default:
err := "unknown literal `%c` in expression `%s`"
return nil, fmt.Errorf("error: "+err, op[0], op)
}
}
type Assign []byte
func assign(src string) (Assign, error) {
out := []byte{}
if len(src) == 1 {
return out, nil
}
for _, c := range src[1:] {
if c >= 'A' && c <= 'Z' {
out = append(out, byte(c))
} else {
err := "unknown literal `%c` in assignment `%s`"
return out, fmt.Errorf("error: "+err, c, src)
}
}
return out, nil
}
type Query []byte
func query(src string) (Query, error) {
out := []byte{}
if len(src) == 1 {
return out, nil
}
for _, c := range src[1:] {
if c >= 'A' && c <= 'Z' {
out = append(out, byte(c))
} else {
err := "unknown literal `%c` in query `%s`"
return out, fmt.Errorf("error: "+err, c, src)
}
}
return out, nil
}
// @rule
type OSRule Rule
func parseOSQuery(src string) (OSRule, error) {
out := OSRule{}
if src == "" {
return out, fmt.Errorf("error: empty rule")
}
if err := checkHs(src, src, "()!+|^", "right"); err != nil {
return out, err
}
src1, err1 := toRPN(src)
if err1 != nil {
return out, err1
}
if err := checkRPN(src1); err != nil {
return out, err
}
src2 := cleanNot(src1)
out1, err2 := makeRule(src2, "A")
if err2 != nil {
return out, err2
}
if len(out1) != 1 {
err := "invalid anonymous query `%s`"
return out, fmt.Errorf("error: "+err, src)
}
return OSRule(out1[0]), nil
}
type Rule struct {
id rune
node TreeNode
}
func parseRule(src string, lhs string, rhs string) ([]Rule, error) {
out := []Rule{}
if err := checkHs(src, lhs, "()!+|^", "left"); err != nil {
return out, err
}
if err := checkHs(src, rhs, "()+", "right"); err != nil {
return out, err
}
lhs1, err1 := toRPN(lhs)
if err1 != nil {
return out, err1
}
rhs1, err2 := toRPN(rhs)
if err2 != nil {
return out, err2
}
if err := checkRPN(rhs1); err != nil {
return out, err
}
if err := checkRPN(lhs1); err != nil {
return out, err
}
rhs1 = cleanNot(rhs1)
lhs1 = cleanNot(lhs1)
rhs2 := simplifyHs(rhs1)
lhs2 := simplifyHs(lhs1)
if err := checkRecDef(src, lhs2, rhs2); err != nil {
return out, err
}
out1, err3 := makeRule(lhs1, rhs2)
if err3 != nil {
return out1, err3
}
return out1, nil
}
func checkRPN(src string) error {
cnt := 0
below := false
for _, c := range src {
if (c >= 'A' && c <= 'Z') || c == '#' {
cnt += 1
} else if inSet(c, "!+|^") {
cnt -= 2
} else {
err := "unknown literal `%c` in `%s`"
return fmt.Errorf("error: "+err, c, src)
}
if cnt < 0 {
below = true
}
//end
if inSet(c, "!+|^") {
cnt += 1
}
}
if cnt == 1 && !below {
return nil
} else {
err := "unknown postfix expression `%s`"
return fmt.Errorf("error: "+err, src)
}
}
func cleanNot(src string) string {
out := []byte{}
for _, c := range src {
if c != '#' {
out = append(out, byte(c))
}
}
return string(out)
}
func checkHs(src string, rule string, set string, hs string) error {
if rule == "" {
err := "empty %s handside in rule `%s`"
return fmt.Errorf("error: "+err, hs, src)
}
for _, c := range rule {
if c >= 'A' && c <= 'Z' || inSet(c, set) {
continue
} else {
err := "unknown literal `%c` in %s handside of rule `%s`"
return fmt.Errorf("error: "+err, c, hs, src)
}
}
return nil
}
func inSet(c rune, s string) bool {
for _, tmp := range s {
if c == tmp {
return true
}
}
return false
}
func toRPN(infix string) (string, error) {
prec := map[rune]int{
'^': 1,
'|': 2,
'+': 4,
'!': 8,
}
out_queue := []byte{}
op_stack := []byte{}
for i, c := range infix {
right_assoc := c == '!'
if c >= 'A' && c <= 'Z' {
out_queue = append(out_queue, byte(c))
} else if inSet(rune(c), "^|+!") {
if c == '!' {
if i < len(infix)-1 {
if infix[i+1] == '(' ||
(infix[i+1] >= 'A' && infix[i+1] <= 'Z') ||
infix[i+1] == '!' {
out_queue = append(out_queue, '#')
} else {
return "", fmt.Errorf("error: stray `!` in `%s`", infix)
}
} else {
return "", fmt.Errorf("error: stray `!` in `%s`", infix)
}
}
if c != '!' {
if i > 0 && i < len(infix)-1 {
l := infix[i-1]
r := infix[i+1]
if !(l == ')' || (l >= 'A' && l <= 'Z')) ||
!(r == '(' || r == '!' || (r >= 'A' && r <= 'Z')) {
return "", fmt.Errorf("error: missing operand in `%s`", infix)
}
} else {
return "", fmt.Errorf("error: missing operand in `%s`", infix)
}
}
p := prec[c]
for len(op_stack) > 0 && ((prec[rune(op_stack[len(op_stack)-1])] > p) ||
((prec[rune(op_stack[len(op_stack)-1])] == p) && !right_assoc)) &&
(op_stack[len(op_stack)-1] != '(') {
out_queue = append(out_queue, op_stack[len(op_stack)-1])
op_stack = op_stack[:len(op_stack)-1]
}
op_stack = append(op_stack, byte(c))
} else if c == '(' {
if i < len(infix)-1 {
if infix[i+1] == ')' {
err := "empty parenthesized expression in `%s`"
return "", fmt.Errorf("error: "+err, infix)
}
}
op_stack = append(op_stack, byte(c))
} else if c == ')' {
for len(op_stack) > 0 && op_stack[len(op_stack)-1] != '(' {
out_queue = append(out_queue, op_stack[len(op_stack)-1])
op_stack = op_stack[:len(op_stack)-1]
}
if len(op_stack) == 0 {
err := "mismatched parentheses in `%s`"
return "", fmt.Errorf("error: "+err, infix)
}
if len(op_stack) > 0 && op_stack[len(op_stack)-1] == '(' {
op_stack = op_stack[:len(op_stack)-1]
}
}
}
for len(op_stack) > 0 {
c := op_stack[len(op_stack)-1]
if inSet(rune(c), "()") {
err := "mismatched parentheses in `%s`"
return "", fmt.Errorf("error: "+err, infix)
}
out_queue = append(out_queue, byte(c))
op_stack = op_stack[:len(op_stack)-1]
}
return string(out_queue), nil
}
func simplifyHs(rhs string) string {
out := ""
for _, c := range rhs {
if c >= 'A' && c <= 'Z' {
out += string(c)
}
}
return out
}
func strrev(s string) string {
runes := []rune(s)
for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
runes[i], runes[j] = runes[j], runes[i]
}
return string(runes)
}
func makeRule(lhs string, rhs string) ([]Rule, error) {
out := []Rule{}
rrhs := strrev(rhs)
for _, c := range rrhs {
node, err := makeNode(lhs)
if err != nil {
return out, err
}
out = append(out, Rule{
id: c,
node: node,
})
}
return out, nil
}
func makeNode(lhs string) (TreeNode, error) {
stack := []TreeNode{}
var tree TreeNode
var t1 TreeNode
var t2 TreeNode
_ = t1
_ = t2
for _, c := range lhs {
if c >= 'A' && c <= 'Z' {
tree = &Value{ch: byte(c)}
stack = append(stack, tree)
} else if c == '!' {
tmp := &UnaryGate{
gType: getType(c),
next: nil,
}
if len(stack) == 0 {
return tree, fmt.Errorf("i-error: stack underflow in `makeNode`")
}
t2 = stack[len(stack)-1]
stack = stack[:len(stack)-1]
tmp.next = t2
tree = tmp
stack = append(stack, tree)
} else {
tmp := &BinaryGate{
gType: getType(c),
left: nil,
right: nil,
}
if len(stack) == 0 {
return tree, fmt.Errorf("i-error: stack underflow in `makeNode`")
}
t1 = stack[len(stack)-1]
stack = stack[:len(stack)-1]
if len(stack) == 0 {
return tree, fmt.Errorf("i-error: stack underflow in `makeNode`")
}
t2 = stack[len(stack)-1]
stack = stack[:len(stack)-1]
tmp.right = t1
tmp.left = t2
tree = tmp
stack = append(stack, tree)
}
}
if len(stack) == 0 {
return tree, fmt.Errorf("i-error: stack underflow in `makeNode`")
}
tree = stack[len(stack)-1]
return tree, nil
}
func getType(c rune) GType {
switch c {
case '!':
return GateNot
case '+':
return GateAnd
case '|':
return GateOr
case '^':
return GateXor
default:
return GateNot
}
}
func checkRecDef(src string, lhs string, rhs string) error {
tmp := [26]int{0}
for _, c := range lhs {
if c >= 'A' && c <= 'Z' {
tmp[int(c)-int('A')] += 1
} else {
err := "unknown literal `%c` in expression `%s`"
return fmt.Errorf("error: "+err, c, src)
}
}
for _, c := range rhs {
if c >= 'A' && c <= 'Z' {
if tmp[int(c)-int('A')] != 0 {
err := "recursive definition of `%c` in expression `%s`"
return fmt.Errorf("error: "+err, c, src)
}
} else {
err := "unknown literal `%c` in expression `%s`"
return fmt.Errorf("error: "+err, c, src)
}
}
return nil
}