first pass at a "builder" interface

internal/gen/ctors.go

@@ -3,8 +3,6 @@ package gen
 import (
 	"bytes"
 	"fmt"
-	"sort"
-	"strconv"
 	"strings"
 	"text/tabwriter"
 
@@ -103,86 +101,6 @@ func (c *ctors) checkargs(i inst.Instruction, s signature) {
 	c.Printf("}\n")
 }
 
-// signature provides access to details about the signature of an instruction function.
-type signature interface {
-	ParameterList() string
-	ParameterName(int) string
-	ParameterSlice() string
-	Length() string
-}
-
-// argslist is the signature for a function with the given named parameters.
-type argslist []string
-
-func (a argslist) ParameterList() string      { return strings.Join(a, ", ") + " avo.Operand" }
-func (a argslist) ParameterName(i int) string { return a[i] }
-func (a argslist) ParameterSlice() string {
-	return fmt.Sprintf("[]avo.Operand{%s}", strings.Join(a, ", "))
-}
-func (a argslist) Length() string { return strconv.Itoa(len(a)) }
-
-// variadic is the signature for a variadic function.
-type variadic struct {
-	name string
-}
-
-func (v variadic) ParameterList() string      { return v.name + " ...avo.Operand" }
-func (v variadic) ParameterName(i int) string { return fmt.Sprintf("%s[%d]", v.name, i) }
-func (v variadic) ParameterSlice() string     { return v.name }
-func (v variadic) Length() string             { return fmt.Sprintf("len(%s)", v.name) }
-
-// niladic is the signature for a function with no arguments.
-type niladic struct{}
-
-func (n niladic) ParameterList() string      { return "" }
-func (n niladic) ParameterName(i int) string { panic("niladic function has no parameters") }
-func (n niladic) ParameterSlice() string     { return "nil" }
-func (n niladic) Length() string             { return "0" }
-
-// params generates the function parameters and a function.
-func params(i inst.Instruction) signature {
-	// Handle the case of forms with multiple arities.
-	switch {
-	case i.IsVariadic():
-		return variadic{name: "ops"}
-	case i.IsNiladic():
-		return niladic{}
-	}
-
-	// Generate nice-looking variable names.
-	n := i.Arity()
-	ops := make([]string, n)
-	count := map[string]int{}
-	for j := 0; j < n; j++ {
-		// Collect unique lowercase bytes from first characters of operand types.
-		s := map[byte]bool{}
-		for _, f := range i.Forms {
-			c := f.Operands[j].Type[0]
-			if 'a' <= c && c <= 'z' {
-				s[c] = true
-			}
-		}
-
-		// Operand name is the sorted bytes.
-		var b []byte
-		for c := range s {
-			b = append(b, c)
-		}
-		sort.Slice(b, func(i, j int) bool { return b[i] < b[j] })
-		name := string(b)
-
-		// Append a counter if we've seen it already.
-		m := count[name]
-		count[name]++
-		if m > 0 {
-			name += strconv.Itoa(m)
-		}
-		ops[j] = name
-	}
-
-	return argslist(ops)
-}
-
 // checkername returns the name of the function that checks an operand of type t.
 func checkername(t string) string {
 	return "operand.Is" + strings.Title(t)