src/syntax/trees/statements/if.ghul

1		namespace Syntax.Trees.Statements is
2		use Source
3
4		use Logging
5
6		use Ghul.Pipes
7
8		class IF: Statement is
9		branches: Collections.Iterable[IF_BRANCH]
10		provides_value: bool => true
11
12		// Set by compile-expressions on a value-consuming if with no
13		// unconditional else: the fall-through path contributes absence,
14		// so generate-il pushes the default of the optional result type
15		// before the join label. Compile-expressions clears it at the
16		// start of each visit_if walk and writes it again on every walk
17		// that reaches the join, so a stale value never survives into a
18		// successful walk's output.
19		yields_absence_on_fall_through: bool public => if_state.yields_absence_on_fall_through, = value is if_state.yields_absence_on_fall_through = value si
20
21		if_state: Syntax.Process.IF_STATE field
22
23		// Expected-type constraint pushed down by compile-expressions.
24		branch_state: Syntax.Process.EXPECTED_TYPE_STATE field
25
26		expected_type: Semantic.Types.Type? => branch_state.expected_type
27		expected_type_error_message: string? => branch_state.expected_type_error_message
28
29		is_tuple_literal: bool =>
30		if branches \|> all(b => b.body.is_tuple_literal) then
31		true
32		else
33		false
34		fi
35
36		init(location: LOCATION, branches: Collections.Iterable[IF_BRANCH]) is
37		super.init(location)
38
39		self.branches = Collections.LIST(branches)
40		si
41
42		debug_location: LOCATION is
43		for branch in branches do
44		return branch.debug_location
45		od
46
47		return location.start_position
48		si
49
50		set_expected_type(expected_type: Semantic.Types.Type?, error_message: string?) is
51		branch_state.set(expected_type, error_message)
52
53		for b in branches do
54		b.body.set_expected_type(expected_type, error_message)
55		od
56		si
57
58		clear() is
59		super.clear()
60		branch_state.clear()
61		if_state.clear()
62		si
63
64		clear_outputs() is
65		super.clear_outputs()
66		if_state.clear()
67		si
68
69		clear_expected_type() is
70		branch_state.clear()
71		si
72
73		accept(visitor: Visitor) is
74		visitor.visit(self)
75		si
76
77		walk(visitor: Visitor) is
78		if !visitor.pre(self) then
79		for branch in branches do
80		branch.walk(visitor)
81		od
82		fi
83
84		accept(visitor)
85		si
86		si
87
88		class IF_BRANCH: Trees.Node, ScopeCarrier is
89		scope: Semantic.Scope? public
90
91		condition: Expressions.Expression?
92		binding: REFUTABLE_BINDING?
93		body: LIST
94
95		init(
96		location: LOCATION,
97		condition: Expressions.Expression?,
98		body: LIST
99		)
100		is
101		init(location, condition, null, body)
102		si
103
104		init(
105		location: LOCATION,
106		condition: Expressions.Expression?,
107		binding: REFUTABLE_BINDING?,
108		body: LIST
109		)
110		is
111		super.init(location)
112
113		self.condition = condition
114		self.binding = binding
115		self.body = body
116		si
117
118		debug_location: LOCATION is
119		if let self.condition? then
120		return location.start_position :: condition.location
121		elif let self.binding? then
122		return location.start_position :: binding.location
123		fi
124
125		return location.start_position
126		si
127
128		accept(visitor: Visitor) is
129		visitor.visit(self)
130		si
131
132		walk(visitor: Visitor) is
133		if !visitor.pre(self) then
134		if let self.condition? then
135		condition.walk(visitor)
136		fi
137
138		if let self.binding? then
139		binding.walk(visitor)
140		fi
141
142		body.walk(visitor)
143		fi
144
145		accept(visitor)
146		si
147		si
148		si