diff options
Diffstat (limited to 'cmd/vartan/compile.go')
-rw-r--r-- | cmd/vartan/compile.go | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/cmd/vartan/compile.go b/cmd/vartan/compile.go new file mode 100644 index 0000000..769f143 --- /dev/null +++ b/cmd/vartan/compile.go @@ -0,0 +1,82 @@ +package main + +import ( + "encoding/json" + "fmt" + "os" + + "github.com/nihei9/vartan/grammar" + "github.com/nihei9/vartan/spec" + "github.com/spf13/cobra" +) + +var compileFlags = struct { + grammar *string + output *string +}{} + +func init() { + cmd := &cobra.Command{ + Use: "compile", + Short: "Compile a grammar into a parsing table", + Example: ` cat grammar | vartan compile -o grammar.json`, + RunE: runCompile, + } + compileFlags.grammar = cmd.Flags().StringP("grammar", "g", "", "grammar file path (default stdin)") + compileFlags.output = cmd.Flags().StringP("output", "o", "", "output file path (default stdout)") + rootCmd.AddCommand(cmd) +} + +func runCompile(cmd *cobra.Command, args []string) (retErr error) { + gram, err := readGrammar(*compileFlags.grammar) + if err != nil { + return err + } + + cgram, err := grammar.Compile(gram) + if err != nil { + return err + } + + err = writeCompiledGrammar(cgram, *compileFlags.output) + if err != nil { + return fmt.Errorf("Cannot write a compiled grammar: %w", err) + } + + return nil +} + +func readGrammar(path string) (*grammar.Grammar, error) { + r := os.Stdin + if path != "" { + f, err := os.Open(path) + if err != nil { + return nil, fmt.Errorf("Cannot open the grammar file %s: %w", path, err) + } + defer f.Close() + r = f + } + ast, err := spec.Parse(r) + if err != nil { + return nil, err + } + return grammar.NewGrammar(ast) +} + +func writeCompiledGrammar(cgram *spec.CompiledGrammar, path string) error { + out, err := json.Marshal(cgram) + if err != nil { + return err + } + w := os.Stdout + if path != "" { + f, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644) + if err != nil { + return fmt.Errorf("Cannot open the output file %s: %w", path, err) + } + defer f.Close() + w = f + } + fmt.Fprintf(w, "%v\n", string(out)) + return nil +} |