💾 Archived View for anachronauts.club › cgi-bin › repos › cgi › gmikit.git › tree › trunk › gmi.go captured on 2021-12-05 at 23:47:19. Gemini links have been rewritten to link to archived content
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1 package gmikit
2
3 import (
4 "bufio"
5 "fmt"
6 "io"
7 "net/url"
8 "strings"
9 )
10
11 type Visitor interface {
12 Begin() error
13 End() error
14 Text(text string) error
15 Link(target *url.URL, friendlyName string) error
16 PreformattingToggle(altText string) error
17 PreformattedText(text string) error
18 Heading1(text string) error
19 Heading2(text string) error
20 Heading3(text string) error
21 UnorderedListItem(text string) error
22 Quote(text string) error
23 }
24
25 func ParseLines(r io.Reader, v Visitor) error {
26 const ws = " \t"
27 pre := false
28 scanner := bufio.NewScanner(r)
29 if err := v.Begin(); err != nil {
30 return err
31 }
32 for scanner.Scan() {
33 text := scanner.Text()
34 if strings.HasPrefix(text, "```") {
35 pre = !pre
36 if err := v.PreformattingToggle(text[3:]); err != nil {
37 return err
38 }
39 } else if pre {
40 if err := v.PreformattedText(text); err != nil {
41 return err
42 }
43 } else if strings.HasPrefix(text, "=>") {
44 text = text[2:]
45 text = strings.TrimLeft(text, ws)
46 split := strings.IndexAny(text, ws)
47 if split == -1 {
48 url, err := url.Parse(text)
49 if err != nil {
50 return err
51 }
52
53 if err = v.Link(url, ""); err != nil {
54 return err
55 }
56 } else {
57 url, err := url.Parse(text[:split])
58 if err != nil {
59 return err
60 }
61
62 name := strings.TrimLeft(text[split:], ws)
63 if err = v.Link(url, name); err != nil {
64 return err
65 }
66 }
67 } else if strings.HasPrefix(text, "*") {
68 text = strings.TrimLeft(text[1:], ws)
69 if err := v.UnorderedListItem(text); err != nil {
70 return err
71 }
72 } else if strings.HasPrefix(text, "###") {
73 text = strings.TrimLeft(text[3:], ws)
74 if err := v.Heading3(text); err != nil {
75 return err
76 }
77 } else if strings.HasPrefix(text, "##") {
78 text = strings.TrimLeft(text[2:], ws)
79 if err := v.Heading2(text); err != nil {
80 return err
81 }
82 } else if strings.HasPrefix(text, "#") {
83 text = strings.TrimLeft(text[1:], ws)
84 if err := v.Heading1(text); err != nil {
85 return err
86 }
87 } else if strings.HasPrefix(text, ">") {
88 text = strings.TrimLeft(text[1:], ws)
89 if err := v.Quote(text); err != nil {
90 return err
91 }
92 } else {
93 if err := v.Text(text); err != nil {
94 return err
95 }
96 }
97 }
98 if err := v.End(); err != nil {
99 return err
100 }
101
102 return scanner.Err()
103 }
104
105 type GmiWriter struct {
106 w io.Writer
107 pre bool
108 }
109
110 func NewGmiWriter(w io.Writer) *GmiWriter {
111 return &GmiWriter{w: w, pre: false}
112 }
113
114 func (g *GmiWriter) Begin() error { return nil }
115 func (g *GmiWriter) End() error { return nil }
116
117 func (g *GmiWriter) Text(text string) error {
118 _, err := fmt.Fprintf(g.w, "%s\n", text)
119 return err
120 }
121
122 func (g *GmiWriter) Link(target *url.URL, friendlyName string) error {
123 if friendlyName == "" {
124 _, err := fmt.Fprintf(g.w, "=> %s\n", target)
125 return err
126 } else {
127 _, err := fmt.Fprintf(g.w, "=> %s %s\n", target, friendlyName)
128 return err
129 }
130 }
131
132 func (g *GmiWriter) PreformattingToggle(altText string) error {
133 if g.pre {
134 g.pre = false
135 _, err := fmt.Fprintf(g.w, "```\n")
136 return err
137 } else {
138 g.pre = true
139 _, err := fmt.Fprintf(g.w, "```%s\n", altText)
140 return err
141 }
142 }
143
144 func (g *GmiWriter) PreformattedText(text string) error {
145 _, err := fmt.Fprintf(g.w, "%s\n", text)
146 return err
147 }
148
149 func (g *GmiWriter) Heading1(text string) error {
150 _, err := fmt.Fprintf(g.w, "# %s\n", text)
151 return err
152 }
153
154 func (g *GmiWriter) Heading2(text string) error {
155 _, err := fmt.Fprintf(g.w, "## %s\n", text)
156 return err
157 }
158
159 func (g *GmiWriter) Heading3(text string) error {
160 _, err := fmt.Fprintf(g.w, "### %s\n", text)
161 return err
162 }
163
164 func (g *GmiWriter) UnorderedListItem(text string) error {
165 _, err := fmt.Fprintf(g.w, "* %s\n", text)
166 return err
167 }
168
169 func (g *GmiWriter) Quote(text string) error {
170 _, err := fmt.Fprintf(g.w, "> %s\n", text)
171 return err
172 }
173
174 func NormalizeGmi(r io.Reader, w io.Writer) error {
175 return ParseLines(r, NewGmiWriter(w))
176 }