70 lines
1.6 KiB
Go
70 lines
1.6 KiB
Go
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package rules
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import (
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"errors"
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"fmt"
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"io"
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"os"
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"strings"
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)
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// NOTE: This parser is non-reentrant due to its dependence on global state.
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// GoLex sadly needs these global variables for storing temporary token/parsing information.
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var yylval *yySymType // For storing extra token information, like the contents of a string.
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var yyline int // Line number within the current file or buffer.
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var yypos int // Character position within the current line.
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var parsedRules []*Rule // Parsed rules.
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type RulesLexer struct {
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errors []string
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}
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func addRule(rule *Rule) {
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parsedRules = append(parsedRules, rule)
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}
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func (lexer *RulesLexer) Lex(lval *yySymType) int {
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yylval = lval
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token_type := yylex()
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return token_type
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}
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func (lexer *RulesLexer) Error(errorStr string) {
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err := fmt.Sprintf("Error parsing rules at line %v, char %v: %v", yyline, yypos, errorStr)
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lexer.errors = append(lexer.errors, err)
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}
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func LoadFromReader(rulesReader io.Reader) ([]*Rule, error) {
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yyin = rulesReader
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yypos = 1
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yyline = 1
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parsedRules = []*Rule{}
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lexer := &RulesLexer{}
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ret := yyParse(lexer)
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if ret != 0 && len(lexer.errors) == 0 {
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lexer.Error("Unknown parser error")
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}
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if len(lexer.errors) > 0 {
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err := errors.New(strings.Join(lexer.errors, "\n"))
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return []*Rule{}, err
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}
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return parsedRules, nil
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}
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func LoadFromString(rulesString string) ([]*Rule, error) {
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rulesReader := strings.NewReader(rulesString)
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return LoadFromReader(rulesReader)
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}
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func LoadFromFile(fileName string) ([]*Rule, error) {
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rulesReader, err := os.Open(fileName)
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if err != nil {
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return []*Rule{}, err
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}
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return LoadFromReader(rulesReader)
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}
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