src/ir/values/protected_region.ghul

1		namespace IR.Values is
2		use Semantic.Types.Type
3
4		// The extent of one `.try` block, shared by every handler attached
5		// to it — a `try` with three catches is three regions over a single
6		// extent.
7		//
8		// SRM delimits a region by four labels and the handler's type,
9		// added to the body's control-flow builder once every one of them
10		// is known — rather than by a nesting whose extents fall out of
11		// the walk. So the boundaries have to be recorded as the walk
12		// passes them and held somewhere until each region closes, which
13		// is what this and PROTECTED_REGION are for.
14		class TRY_EXTENT is
15		start: int public
16		end: int public
17
18		init() is
19		start = -1
20		end = -1
21		si
22		si
23
24		// One handler over an extent: a catch of `catch_type`, or — when
25		// that is null — a finally.
26		class PROTECTED_REGION is
27		extent: TRY_EXTENT
28		catch_type: Type?
29
30		// A catch over a framework type the compilation has no symbol
31		// for, named the way the assert helper names its exception.
32		// Set instead of `catch_type`, never alongside it.
33		catch_type_name: (assembly: string, `namespace: string, name: string)?
34
35		handler_start: int public
36		handler_end: int public
37
38		init(extent: TRY_EXTENT, catch_type: Type?) is
39		self.extent = extent
40		self.catch_type = catch_type
41		self.catch_type_name = null
42
43		handler_start = -1
44		handler_end = -1
45		si
46
47		init(
48		extent: TRY_EXTENT,
49		assembly: string,
50		`namespace: string,
51		name: string
52		) is
53		self.extent = extent
54		self.catch_type = null
55		self.catch_type_name = (assembly = assembly, `namespace = `namespace, name = name)
56
57		handler_start = -1
58		handler_end = -1
59		si
60
61		is_catch: bool => catch_type? \/ catch_type_name?
62
63		// The caught type as it reads in this value's description.
64		catch_type_il: string =>
65		if let type = catch_type then
66		"{type}"
67		elif let named = catch_type_name then
68		"{named.`namespace}.{named.name}"
69		else
70		""
71		fi
72		si
73
74		// `.try {`
75		class TRY_START: Value is
76		_extent: TRY_EXTENT
77
78		init(extent: TRY_EXTENT) is
79		super.init()
80
81		_extent = extent
82		si
83
84		gen(context: IR.CONTEXT) is
85		let body = context.current_srm_body_emitter!
86		_extent.start = body.mark_region_boundary()
87		si
88
89		to_string() -> string => ".try {{"
90		si
91
92		// The `}` closing a `.try` block.
93		class TRY_END: Value is
94		_extent: TRY_EXTENT
95
96		init(extent: TRY_EXTENT) is
97		super.init()
98
99		_extent = extent
100		si
101
102		gen(context: IR.CONTEXT) is
103		let body = context.current_srm_body_emitter!
104		_extent.end = body.mark_region_boundary()
105		si
106
107		to_string() -> string => "}} // try"
108		si
109
110		// `catch T {` or `finally {`
111		class HANDLER_START: Value is
112		_region: PROTECTED_REGION
113
114		init(region: PROTECTED_REGION) is
115		super.init()
116
117		_region = region
118		si
119
120		gen(context: IR.CONTEXT) is
121		let body = context.current_srm_body_emitter!
122		_region.handler_start = body.mark_region_boundary()
123		si
124
125		to_string() -> string =>
126		if _region.is_catch then
127		"catch {_region.catch_type_il} {{"
128		else
129		"finally {{"
130		fi
131		si
132
133		// The `}` closing a handler, and the point at which every boundary
134		// of the region is known — so this is where the region is added.
135		//
136		// Adding it here rather than in some later sweep is what keeps the
137		// ordering right: ECMA-335 requires regions be listed innermost
138		// first, and a region nested inside another closes before it does.
139		// Nothing validates the order, and getting it wrong produces an
140		// assembly that loads and then runs the wrong handler, so the
141		// ordering wants to fall out of the structure rather than be
142		// arranged separately.
143		class HANDLER_END: Value is
144		_region: PROTECTED_REGION
145
146		init(region: PROTECTED_REGION) is
147		super.init()
148
149		_region = region
150		si
151
152		gen(context: IR.CONTEXT) is
153		let body = context.current_srm_body_emitter!
154		_region.handler_end = body.mark_region_boundary()
155
156		if _region.is_catch then
157		let token =
158		if let catch_type = _region.catch_type then
159		context.resolve_type_token(catch_type)
160		else
161		(
162		let named = _region.catch_type_name!
163
164		context.resolve_type_token_by_name(
165		named.assembly, named.`namespace, named.name)
166		)
167		fi
168
169		body.add_catch_region(
170		_region.extent.start,
171		_region.extent.end,
172		_region.handler_start,
173		_region.handler_end,
174		token)
175		else
176		body.add_finally_region(
177		_region.extent.start,
178		_region.extent.end,
179		_region.handler_start,
180		_region.handler_end)
181		fi
182		si
183
184		to_string() -> string => "}} // handler"
185		si
186		si