Method generateGroupedCases

pkg/codegen/match.go:205–228

generateGroupedCases groups arms by pattern type and generates cases. This is critical for handling guarded patterns: - Multiple arms for the same constructor become if/else chain in one case - Avoids duplicate case clauses which are illegal in Go

(typeSwitch bool)

// - Multiple arms for the same constructor become if/else chain in one case
// - Avoids duplicate case clauses which are illegal in Go
func (g *MatchCodeGen) generateGroupedCases(typeSwitch bool) {
	// Group arms by their case key (type name for constructors, "default" for wildcards)
	groups := make(map[string]*armGroup)
	var order []string // Preserve order

	for _, arm := range g.Match.Arms {
		key := g.getPatternCaseKey(arm.Pattern)

		if _, exists := groups[key]; !exists {
			groups[key] = &armGroup{
				typeName:  key,
				isDefault: key == "default",
			}
			order = append(order, key)
		}
		groups[key].arms = append(groups[key].arms, arm)
	}

	// Generate case for each group
	for _, key := range order {
		group := groups[key]
		g.generateGroupedCase(group, typeSwitch)
	}
}

// getPatternCaseKey returns the case key for a pattern.
// Constructor patterns return their full type name.