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