controllogic: add Value union + sizing helpers (port of arraypolicy.ts)

internal/controllogic/value.go

@@ -0,0 +1,156 @@
+// Value model for control-logic locals/expressions. A Value is either a scalar
+// (float64; booleans are 1/0) or an array ([]Value). This is the Go port of
+// web/src/lib/arraypolicy.ts (sizing) plus the asNum/asArr/idx narrowing from
+// web/src/lib/expr.ts. Pure, dependency-free.
+package controllogic
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+)
+
+// Value is a scalar (float64) or an array ([]Value).
+type Value = any
+
+// ARRAY_MAX is the global hard cap on dynamic array length (drops oldest).
+const ARRAY_MAX = 1_000_000
+
+// StateVar declares a graph-local variable. Mirrors web/src/lib/types.ts StateVar.
+type StateVar struct {
+	Name     string  `json:"name"`
+	Type     string  `json:"type,omitempty"` // number|bool|string|array (default number)
+	Initial  string  `json:"initial"`        // initial value, stored as a string
+	Unit     string  `json:"unit,omitempty"`
+	Low      float64 `json:"low,omitempty"`
+	High     float64 `json:"high,omitempty"`
+	Elem     string  `json:"elem,omitempty"`     // array-only: number|bool|array
+	Sizing   string  `json:"sizing,omitempty"`   // array-only: dynamic|capped|fixed
+	Capacity int     `json:"capacity,omitempty"` // array-only
+}
+
+func asNum(v Value) (float64, error) {
+	f, ok := v.(float64)
+	if !ok {
+		return 0, fmt.Errorf("expected a number, got an array")
+	}
+	return f, nil
+}
+
+func asArr(v Value) ([]Value, error) {
+	a, ok := v.([]Value)
+	if !ok {
+		return nil, fmt.Errorf("expected an array, got a number")
+	}
+	return a, nil
+}
+
+// idxResolve resolves a possibly-negative index against length; range-checked.
+func idxResolve(i float64, length int) (int, error) {
+	k := int(i) // truncates toward zero, matching Math.trunc
+	if k < 0 {
+		k = length + k
+	}
+	if k < 0 || k >= length {
+		return 0, fmt.Errorf("index %v out of range (len %d)", i, length)
+	}
+	return k, nil
+}
+
+// normalizeValue coerces an arbitrary decoded value (e.g. from JSON: float64,
+// bool, []interface{}) into a canonical Value (float64 leaves, []Value arrays).
+func normalizeValue(v any) Value {
+	switch t := v.(type) {
+	case float64:
+		return t
+	case float32:
+		return float64(t)
+	case int:
+		return float64(t)
+	case int64:
+		return float64(t)
+	case bool:
+		if t {
+			return 1.0
+		}
+		return 0.0
+	case []interface{}:
+		out := make([]Value, len(t))
+		for i, e := range t {
+			out[i] = normalizeValue(e)
+		}
+		return out
+	default:
+		return 0.0
+	}
+}
+
+func zeroFill(n int) []Value {
+	if n < 0 {
+		n = 0
+	}
+	out := make([]Value, n)
+	for i := range out {
+		out[i] = 0.0
+	}
+	return out
+}
+
+// parseInitialArray returns the starting contents of an array local. Mirrors
+// arraypolicy.ts parseInitialArray.
+func parseInitialArray(sv StateVar) []Value {
+	cap := sv.Capacity
+	raw := strings.TrimSpace(sv.Initial)
+	var parsed []Value
+	if raw != "" {
+		var j interface{}
+		if err := json.Unmarshal([]byte(raw), &j); err == nil {
+			if arr, ok := j.([]interface{}); ok {
+				parsed = normalizeValue(arr).([]Value)
+			}
+		}
+	}
+	if sv.Sizing == "fixed" {
+		if parsed == nil {
+			return zeroFill(cap)
+		}
+		out := make([]Value, 0, cap)
+		for i := 0; i < len(parsed) && i < cap; i++ {
+			out = append(out, parsed[i])
+		}
+		for len(out) < cap {
+			out = append(out, 0.0)
+		}
+		return out
+	}
+	if parsed == nil {
+		return []Value{}
+	}
+	return parsed
+}
+
+// applySizing clamps arr to the declared sizing policy. Mirrors arraypolicy.ts.
+func applySizing(arr []Value, sv StateVar) []Value {
+	cap := sv.Capacity
+	switch sv.Sizing {
+	case "fixed":
+		out := make([]Value, 0, cap)
+		for i := 0; i < len(arr) && i < cap; i++ {
+			out = append(out, arr[i])
+		}
+		for len(out) < cap {
+			out = append(out, 0.0)
+		}
+		return out
+	case "capped":
+		if len(arr) > cap {
+			return arr[len(arr)-cap:]
+		}
+		return arr
+	default:
+		if len(arr) > ARRAY_MAX {
+			return arr[len(arr)-ARRAY_MAX:]
+		}
+		return arr
+	}
+}