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66
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1 package gcss
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2
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3 import (
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4 "fmt"
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5 "io"
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6 "strings"
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7 )
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8
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9 // variable represents a GCSS variable.
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10 type variable struct {
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11 elementBase
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12 name string
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13 value string
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14 }
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15
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16 // WriteTo writes the variable to the writer.
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17 func (v *variable) WriteTo(w io.Writer) (int64, error) {
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18 n, err := w.Write([]byte(v.value))
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19
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20 return int64(n), err
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21 }
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22
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23 // variableNV extracts a variable name and value
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24 // from the line.
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25 func variableNV(ln *line) (string, string, error) {
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26 s := strings.TrimSpace(ln.s)
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27
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28 if !strings.HasPrefix(s, dollarMark) {
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29 return "", "", fmt.Errorf("variable must start with %q [line: %d]", dollarMark, ln.no)
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30 }
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31
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32 nv := strings.SplitN(s, space, 2)
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33
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34 if len(nv) < 2 {
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35 return "", "", fmt.Errorf("variable's name and value should be divided by a space [line: %d]", ln.no)
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36 }
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37
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38 if !strings.HasSuffix(nv[0], colon) {
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39 return "", "", fmt.Errorf("variable's name should end with a colon [line: %d]", ln.no)
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40 }
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41
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42 return strings.TrimSuffix(strings.TrimPrefix(nv[0], dollarMark), colon), nv[1], nil
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43 }
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44
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45 // newVariable creates and returns a variable.
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46 func newVariable(ln *line, parent element) (*variable, error) {
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47 name, value, err := variableNV(ln)
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48
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49 if err != nil {
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50 return nil, err
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51 }
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52
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53 if strings.HasSuffix(value, semicolon) {
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54 return nil, fmt.Errorf("variable must not end with %q", semicolon)
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55 }
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56
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57 return &variable{
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58 elementBase: newElementBase(ln, parent),
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59 name: name,
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60 value: value,
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61 }, nil
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62 }
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