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|
// nolint: golint
package main
import (
"io"
"strings"
"github.com/alecthomas/participle/v2/lexer"
)
// Parse a BASIC program.
func Parse(r io.Reader) (*Program, error) {
program, err := basicParser.Parse("", r)
if err != nil {
return nil, err
}
program.init()
return program, nil
}
type Program struct {
Pos lexer.Position
Commands []*Command `@@*`
Table map[int]*Command
}
type Command struct {
Pos lexer.Position
Index int
Line int `@Number`
Remark *Remark `( @@`
Input *Input ` | @@`
Let *Let ` | @@`
Goto *Goto ` | @@`
If *If ` | @@`
Print *Print ` | @@`
Call *Call ` | @@ ) EOL`
}
type Remark struct {
Pos lexer.Position
Comment string `@Comment`
}
type Call struct {
Pos lexer.Position
Name string `@Ident`
Args []*Expression `"(" ( @@ ( "," @@ )* )? ")"`
}
type Print struct {
Pos lexer.Position
Expression *Expression `"PRINT" @@`
}
type Input struct {
Pos lexer.Position
Variable string `"INPUT" @Ident`
}
type Let struct {
Pos lexer.Position
Variable string `"LET" @Ident`
Value *Expression `"=" @@`
}
type Goto struct {
Pos lexer.Position
Line int `"GOTO" @Number`
}
type If struct {
Pos lexer.Position
Condition *Expression `"IF" @@`
Line int `"THEN" @Number`
}
type Operator string
func (o *Operator) Capture(s []string) error {
*o = Operator(strings.Join(s, ""))
return nil
}
type Value struct {
Pos lexer.Position
Number *float64 ` @Number`
Variable *string `| @Ident`
String *string `| @String`
Call *Call `| @@`
Subexpression *Expression `| "(" @@ ")"`
}
type Factor struct {
Pos lexer.Position
Base *Value `@@`
Exponent *Value `( "^" @@ )?`
}
type OpFactor struct {
Pos lexer.Position
Operator Operator `@("*" | "/")`
Factor *Factor `@@`
}
type Term struct {
Pos lexer.Position
Left *Factor `@@`
Right []*OpFactor `@@*`
}
type OpTerm struct {
Pos lexer.Position
Operator Operator `@("+" | "-")`
Term *Term `@@`
}
type Cmp struct {
Pos lexer.Position
Left *Term `@@`
Right []*OpTerm `@@*`
}
type OpCmp struct {
Pos lexer.Position
Operator Operator `@("=" | "<" "=" | ">" "=" | "<" | ">" | "!" "=")`
Cmp *Cmp `@@`
}
type Expression struct {
Pos lexer.Position
Left *Cmp `@@`
Right []*OpCmp `@@*`
}
|
