104 lines
2.1 KiB
Go
104 lines
2.1 KiB
Go
package parser
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import (
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"errors"
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"strconv"
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"strings"
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"github.com/hellerve/argos/ast"
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)
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func withoutEmpty(input []string) []string {
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var r []string
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for _, str := range input {
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if str != "" {
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r = append(r, str)
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}
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}
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return r
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}
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func tokenize(input string) []string {
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return withoutEmpty(strings.Split(strings.Replace(strings.Replace(input, "(", " ( ", -1), ")", " ) ", -1), " "))
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}
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func parseValue(input []string) (*ast.AST, error, []string) {
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var res ast.AST
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f, err := strconv.ParseFloat(input[0], 64)
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if err == nil {
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res = ast.AST{ast.Num, f}
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return &res, nil, input[1:]
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}
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if input[0][0] == '"' {
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var agg []string
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for {
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if len(input) == 0 {
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return nil, errors.New("Unmatched \""), input
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}
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token := input[0]
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input = input[1:]
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agg = append(agg, token)
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if token[len(token)-1] == '"' {
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break
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}
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}
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res = ast.AST{ast.String, strings.Join(agg, " ")}
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return &res, nil, input
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}
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res = ast.AST{ast.Symbol, input[0]}
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return &res, nil, input[1:]
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}
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func parseToken(input []string) (*ast.AST, error, []string) {
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if len(input) == 0 {
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return nil, errors.New("Unmatched '('"), input
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}
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if input[0][0] == '\'' {
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if (input[0] == "'") {
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input = input[1:]
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} else {
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input = append([]string{input[0][1:]}, input[1:]...)
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}
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tmp, err, input := parseToken(input)
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if err != nil {
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return nil, err, input
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}
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res := ast.AST{ast.List, []ast.AST{ast.AST{ast.Symbol, "quote"}, *tmp}}
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return &res, nil, input
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}
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switch input[0] {
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case "(": {
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var l []ast.AST
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input = input[1:]
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for input[0] != ")" {
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elem, err, newInput := parseToken(input)
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if err != nil {
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return nil, err, input
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}
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l = append(l, *elem)
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input = newInput
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}
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res := ast.AST{ast.List, l}
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return &res, nil, input[1:]
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}
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case ")": {
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return nil, errors.New("Unmatched ')'"), input
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}
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}
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return parseValue(input)
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}
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func Parse(input string) (*ast.AST, error, []string) {
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return parseToken(tokenize(input))
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}
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