forked from shanemhansen/gosp
/
compiler.go
165 lines (157 loc) · 3.33 KB
/
compiler.go
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package gosp
import (
"bufio"
"fmt"
"io"
"strings"
)
// KeyValue is a simple hash type
type KeyValue [2]string
// Compiler directives such as import and type declarations
type Directive struct {
Imports []string
Params []KeyValue
}
var printedMeta = false
// Compile operates on the steam provided by in, writing output to out
// funcName and packageName define the package that the generated code should
// inhabit. funcName determines name of the generated closure.
// By default for a/{b,c}.go packageName is "c" and funcName is "A", and "B".
func Compile(in io.Reader, out io.Writer, funcName, packageName string) {
reader := bufio.NewReader(in)
directive := Directive{}
//process all directives at beginning of file
for {
//check for line beginnig with '@'
peekaboo, err := reader.Peek(1)
if err == io.EOF {
break
}
if err != nil {
panic(err)
}
if peekaboo[0] != '@' {
break
}
//found line, read it in and process it.
line, err := reader.ReadString('\n')
if err != nil {
panic(err)
}
if strings.HasPrefix(line, "@import") {
directive.Imports = append(directive.Imports, line[1:])
continue
}
if strings.HasPrefix(line, "@(") {
line = line[2 : len(line)-2]
for _, parameter := range strings.Split(line, ",") {
parameter := strings.Trim(parameter, " ")
kv := strings.Split(parameter, " ")
param := KeyValue{kv[0], kv[1]}
directive.Params = append(directive.Params, param)
}
continue
}
}
data := make([]byte, 1)
LITERAL_OUTPUT := 0
CODE := 1
WAITINGFORBEGINCODE := 2
WAITINGFORENDCODE := 3
state := LITERAL_OUTPUT
fmt.Fprintf(out,
`package %s
import "fmt"
import "io"
`, packageName)
for _, pkg := range directive.Imports {
fmt.Fprintf(out, "%s\n", pkg)
}
if !printedMeta {
printedMeta = true
out.Write([]byte(`
var _ fmt.Stringer
type Template func(io.Writer)
`))
}
var params string
for _, param := range directive.Params {
params += "," + param[0] + " " + param[1]
}
if len(params) == 0 {
params = ""
} else {
params = params[1:]
}
fmt.Fprintf(out,
`func %s(%s) (func(io.Writer)) {
return func(output io.Writer) {
output.Write([]byte(%s`,
funcName,
params,
"`",
)
counter := 0
expressionFlag := 0
OUTER:
for {
n, err := reader.Read(data)
switch err {
case io.EOF:
break OUTER
case nil:
break
default:
panic(err)
}
if n != len(data) {
panic("short read")
}
char := data[0]
counter++
switch state {
case LITERAL_OUTPUT:
if char == '<' {
state = WAITINGFORBEGINCODE
counter = 0
} else {
out.Write([]byte{char})
}
case CODE:
if char == '%' {
state = WAITINGFORENDCODE
counter = 0
} else if char == '=' && counter == 1 {
expressionFlag = 1
out.Write([]byte(`fmt.Fprintf(output, "%v",`))
} else {
out.Write([]byte{char})
}
case WAITINGFORBEGINCODE:
if char == '%' {
state = CODE
counter = 0
out.Write([]byte("`))\n"))
} else {
out.Write([]byte{'<', char})
state = LITERAL_OUTPUT
counter = 0
}
case WAITINGFORENDCODE:
if char == '>' {
state = LITERAL_OUTPUT
counter = 0
if expressionFlag == 1 {
expressionFlag = 0
out.Write([]byte(")"))
}
out.Write([]byte("\noutput.Write([]byte(`"))
} else {
out.Write([]byte{'%'})
state = CODE
counter = 0
}
}
}
out.Write([]byte("`))\n}\n}\n"))
}