115 lines
2.3 KiB
Go
115 lines
2.3 KiB
Go
package field
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import (
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"io"
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)
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// 32-bit Befunge-98
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// =================
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// |-2,147,483,648
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// |
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// | x
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// -----+-----
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// -2,147,483,648 | 2,147,483,647
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// |
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// y|2,147,483,647
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type Field struct {
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x int
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y int
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lx int
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ly int
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lines []Line
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}
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type Line struct {
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x int
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l int
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columns []int
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}
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func Load(fd io.Reader) (*Field, error) {
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f := new(Field)
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l := new(Line)
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trailingSpaces := 0
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lastReadIsCR := false
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for {
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data := make([]byte, 4096)
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if n, errRead := fd.Read(data); errRead != nil {
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if errRead == io.EOF {
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if f.ly == 0 {
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if l.l == 0 {
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return nil, newDecodeError("No instruction on the first line of the file produces an unusable program in Befunge98")
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}
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f.x = l.x
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}
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if l.l > 0 {
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f.ly++
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if f.x < l.x {
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f.x = l.x
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}
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if f.lx < l.l+l.x-f.x {
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f.lx = l.l + l.x - f.x
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}
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f.lines = append(f.lines, *l)
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}
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break
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} else {
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return nil, newReadError(errRead)
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}
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} else {
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for i := 0; i < n; i++ {
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if data[i] == ' ' {
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continue
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}
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if lastReadIsCR && data[i] == '\n' {
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lastReadIsCR = false
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continue
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}
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if data[i] == '\n' || data[i] == '\r' {
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if f.ly == 0 {
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if l.l == 0 {
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return nil, newDecodeError("No instruction on the first line of the file produces an unusable program in Befunge98")
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}
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f.x = l.x
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}
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f.ly++
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if l.l > 0 {
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if f.x > l.x {
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f.x = l.x
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}
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if f.lx < l.l+l.x-f.x {
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f.lx = l.l + l.x - f.x
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}
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}
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f.lines = append(f.lines, *l)
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l = new(Line)
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trailingSpaces = 0
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if data[i] == '\r' {
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if i+1 < n && data[i+1] == '\n' {
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i++
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} else {
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lastReadIsCR = true
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}
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}
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} else {
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if l.l == 0 && data[i] == ' ' {
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l.x++ // trim leading spaces
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} else {
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if data[i] == ' ' {
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trailingSpaces++
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} else {
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for j := 0; j < trailingSpaces; j++ {
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l.columns = append(l.columns, ' ')
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}
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l.l += trailingSpaces + 1
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trailingSpaces = 0
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l.columns = append(l.columns, int(data[i]))
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}
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}
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}
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}
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}
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}
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return f, nil
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}
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