scratch/blo/blox.go (view raw)
| 1 | package main |
| 2 | |
| 3 | import ( |
| 4 | "errors" |
| 5 | "fmt" |
| 6 | "io" |
| 7 | "net/http" |
| 8 | "os" |
| 9 | "strings" |
| 10 | ) |
| 11 | |
| 12 | var escope = EvalScope{ |
| 13 | Vars: map[string]Expr{ |
| 14 | "my_name": { |
| 15 | Type: ExprStr, |
| 16 | AsStr: "Olex", |
| 17 | }, |
| 18 | }, |
| 19 | Funcs: map[string]Func{ |
| 20 | "let": func(ctx *EvalContext, args []Expr) (Expr, error) { |
| 21 | if len(args) != 2 { |
| 22 | return Expr{}, errors.New("let() expects two arguments") |
| 23 | } |
| 24 | |
| 25 | if args[0].Type != ExprVar { |
| 26 | return Expr{}, errors.New("First argument of let() has to be variable name") |
| 27 | } |
| 28 | |
| 29 | name := args[0].AsVar |
| 30 | value, err := ctx.EvalExpr(args[1]) |
| 31 | if err != nil { |
| 32 | return Expr{}, err |
| 33 | } |
| 34 | |
| 35 | ctx.TopScope().Vars[name] = value |
| 36 | return Expr{}, nil |
| 37 | }, |
| 38 | |
| 39 | "define": func(ctx *EvalContext, args []Expr) (Expr, error) { |
| 40 | if len(args) < 2 { |
| 41 | return Expr{}, errors.New("define() expects at least 2 arguments") |
| 42 | } |
| 43 | |
| 44 | if args[0].Type != ExprVar { |
| 45 | return Expr{}, errors.New("define(): first argument must be the name of the function") |
| 46 | } |
| 47 | |
| 48 | funName := args[0].AsVar |
| 49 | if args[1].Type != ExprFuncall || args[1].AsFuncall.Name != "args" { |
| 50 | return Expr{}, errors.New("define(): second argument must be the argument list") |
| 51 | } |
| 52 | |
| 53 | funArgs := args[1].AsFuncall.Args |
| 54 | for _, funArg := range funArgs { |
| 55 | if funArg.Type != ExprVar { |
| 56 | return Expr{}, errors.New("define(): argument list must consist of only variable names") |
| 57 | } |
| 58 | } |
| 59 | |
| 60 | ctx.TopScope().Funcs[funName] = func(context *EvalContext, callArgs []Expr) (Expr, error) { |
| 61 | scope := EvalScope{ |
| 62 | Vars: map[string]Expr{}, |
| 63 | Funcs: map[string]Func{}, |
| 64 | } |
| 65 | |
| 66 | if len(callArgs) != len(funArgs) { |
| 67 | return Expr{}, errors.New(fmt.Sprintf("%s(): expected %d arguments but provided %d", funName, len(funArgs), len(args))) |
| 68 | } |
| 69 | |
| 70 | for index := range callArgs { |
| 71 | scope.Vars[funArgs[index].AsVar] = callArgs[index] |
| 72 | } |
| 73 | |
| 74 | context.PushScope(scope) |
| 75 | for _, stmt := range args[2:] { |
| 76 | _, err := context.EvalExpr(stmt) |
| 77 | if err != nil { |
| 78 | return Expr{}, err |
| 79 | } |
| 80 | } |
| 81 | context.PopScope() |
| 82 | |
| 83 | return Expr{}, nil |
| 84 | } |
| 85 | |
| 86 | return Expr{}, nil |
| 87 | }, |
| 88 | |
| 89 | "say": func(context *EvalContext, args []Expr) (Expr, error) { |
| 90 | for _, arg := range args { |
| 91 | val, err := context.EvalExpr(arg) |
| 92 | if err != nil { |
| 93 | return Expr{}, err |
| 94 | } |
| 95 | |
| 96 | switch val.Type { |
| 97 | case ExprStr: |
| 98 | fmt.Printf("%s", val.AsStr) |
| 99 | |
| 100 | case ExprInt: |
| 101 | fmt.Printf("%d", val.AsInt) |
| 102 | default: |
| 103 | return Expr{}, errors.New("say() expects its arguments to be strings or numbers") |
| 104 | } |
| 105 | } |
| 106 | fmt.Printf("\n") |
| 107 | return Expr{}, nil |
| 108 | }, |
| 109 | |
| 110 | "http": func(context *EvalContext, args []Expr) (Expr, error) { |
| 111 | var url strings.Builder |
| 112 | for _, arg := range args { |
| 113 | val, err := context.EvalExpr(arg) |
| 114 | if err != nil { |
| 115 | return Expr{}, err |
| 116 | } |
| 117 | if val.Type != ExprStr { |
| 118 | return Expr{}, errors.New("http() expects its arguments to be strings") |
| 119 | } |
| 120 | fmt.Fprint(&url, val.AsStr) |
| 121 | } |
| 122 | |
| 123 | resp, err := http.Get(url.String()) |
| 124 | if err != nil { |
| 125 | return Expr{}, err |
| 126 | } |
| 127 | defer resp.Body.Close() |
| 128 | |
| 129 | body, err := io.ReadAll(resp.Body) |
| 130 | if err != nil { |
| 131 | return Expr{}, err |
| 132 | } |
| 133 | |
| 134 | return Expr{ |
| 135 | Type: ExprStr, |
| 136 | AsStr: string(body), |
| 137 | }, nil |
| 138 | }, |
| 139 | }, |
| 140 | } |
| 141 | |
| 142 | func main() { |
| 143 | ctx := EvalContext{} |
| 144 | ctx.PushScope(escope) |
| 145 | |
| 146 | if len(os.Args) < 2 { |
| 147 | fmt.Fprintf(os.Stderr, "ERROR: no input is provided\n") |
| 148 | os.Exit(1) |
| 149 | } |
| 150 | |
| 151 | fpath := os.Args[1] |
| 152 | content, err := os.ReadFile(fpath) |
| 153 | if err != nil { |
| 154 | fmt.Fprintf(os.Stderr, "ERROR: could not read file %s: %s\n", fpath, err) |
| 155 | os.Exit(1) |
| 156 | } |
| 157 | |
| 158 | lexer := NewLexer([]rune(string(content)), fpath) |
| 159 | |
| 160 | exprs, err := ParseExprs(&lexer) |
| 161 | if err != nil { |
| 162 | fmt.Fprintln(os.Stderr, err) |
| 163 | os.Exit(1) |
| 164 | } |
| 165 | |
| 166 | for _, expr := range exprs { |
| 167 | if _, err := ctx.EvalExpr(expr); err != nil { |
| 168 | fmt.Fprintln(os.Stderr, err) |
| 169 | os.Exit(1) |
| 170 | } |
| 171 | } |
| 172 | } |