54 lines
1.2 KiB
Go
54 lines
1.2 KiB
Go
package engine
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import (
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"bufio"
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"context"
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"fmt"
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"io"
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"log"
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"strings"
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)
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// Loop starts an engine execution loop with the given symbol as the starting node.
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//
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// The root reads inputs from the provided reader, one line at a time.
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//
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// It will execute until running out of bytecode in the buffer.
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//
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// Any error not handled by the engine will terminate the oop and return an error.
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//
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// Rendered output is written to the provided writer.
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func Loop(en *Engine, reader io.Reader, writer io.Writer, ctx context.Context) error {
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var err error
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_, err = en.WriteResult(writer, ctx)
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if err != nil {
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return err
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}
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writer.Write([]byte{0x0a})
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running := true
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bufReader := bufio.NewReader(reader)
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for running {
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in, err := bufReader.ReadString('\n')
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if err == io.EOF {
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log.Printf("EOF found, that's all folks")
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return nil
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}
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if err != nil {
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return fmt.Errorf("cannot read input: %v\n", err)
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}
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in = strings.TrimSpace(in)
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running, err = en.Exec([]byte(in), ctx)
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if err != nil {
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return fmt.Errorf("unexpected termination: %v\n", err)
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}
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_, err = en.WriteResult(writer, ctx)
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if err != nil {
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return err
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}
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writer.Write([]byte{0x0a})
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}
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return nil
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}
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