37 Commits

Author SHA1 Message Date
JiaLiPassion
ef4736d052 build: update jasmine to 3.5 (#34625)
1. update jasmine to 3.5
2. update @types/jasmine to 3.5
3. update @types/jasminewd2 to 2.0.8

Also fix several cases, the new jasmine 3 will help to create test cases correctly,
such as in the `jasmine 2.x` version, the following case will pass

```
expect(1 == 2);
```

But in jsamine 3, the case will need to be

```
expect(1 == 2).toBeTrue();
```

PR Close #34625
2020-04-08 12:10:34 -07:00
JoostK
64022f51d4 fix(compiler): resolve enum values in binary operations (#36461)
During static evaluation of expressions, the partial evaluator
may come across a binary + operator for which it needs to
evaluate its operands. Any of these operands may be a reference
to an enum member, in which case the enum member's value needs
to be used as literal value, not the enum member reference
itself. This commit fixes the behavior by resolving an
`EnumValue` when used as a literal value.

Fixes #35584
Resolves FW-1951

PR Close #36461
2020-04-07 15:21:51 -07:00
JoostK
f9f6e2e1b3 style(compiler): reformat partial evaluator source tree (#36461)
PR Close #36461
2020-04-07 15:21:51 -07:00
George Kalpakas
bd6a39c364 fix(ngcc): correctly detect emitted TS helpers in ES5 (#35191)
In ES5 code, TypeScript requires certain helpers (such as
`__spreadArrays()`) to be able to support ES2015+ features. These
helpers can be either imported from `tslib` (by setting the
`importHelpers` TS compiler option to `true`) or emitted inline (by
setting the `importHelpers` and `noEmitHelpers` TS compiler options to
`false`, which is the default value for both).

Ngtsc's `StaticInterpreter` (which is also used during ngcc processing)
is able to statically evaluate some of these helpers (currently
`__assign()`, `__spread()` and `__spreadArrays()`), as long as
`ReflectionHost#getDefinitionOfFunction()` correctly detects the
declaration of the helper. For this to happen, the left-hand side of the
corresponding call expression (i.e. `__spread(...)` or
`tslib.__spread(...)`) must be evaluated as a function declaration for
`getDefinitionOfFunction()` to be called with.

In the case of imported helpers, the `tslib.__someHelper` expression was
resolved to a function declaration of the form
`export declare function __someHelper(...args: any[][]): any[];`, which
allows `getDefinitionOfFunction()` to correctly map it to a TS helper.

In contrast, in the case of emitted helpers (and regardless of the
module format: `CommonJS`, `ESNext`, `UMD`, etc.)), the `__someHelper`
identifier was resolved to a variable declaration of the form
`var __someHelper = (this && this.__someHelper) || function () { ... }`,
which upon further evaluation was categorized as a `DynamicValue`
(prohibiting further evaluation by the `getDefinitionOfFunction()`).

As a result of the above, emitted TypeScript helpers were not evaluated
in ES5 code.

---
This commit changes the detection of TS helpers to leverage the existing
`KnownFn` feature (previously only used for built-in functions).
`Esm5ReflectionHost` is changed to always return `KnownDeclaration`s for
TS helpers, both imported (`getExportsOfModule()`) as well as emitted
(`getDeclarationOfIdentifier()`).

Similar changes are made to `CommonJsReflectionHost` and
`UmdReflectionHost`.

The `KnownDeclaration`s are then mapped to `KnownFn`s in
`StaticInterpreter`, allowing it to statically evaluate call expressions
involving any kind of TS helpers.

Jira issue: https://angular-team.atlassian.net/browse/FW-1689

PR Close #35191
2020-02-21 09:06:46 -08:00
Paul Gschwendtner
6b468f9b2e fix(ngcc): libraries using spread in object literals cannot be processed (#34661)
Consider a library that uses a shared constant for host bindings. e.g.

```ts
export const BASE_BINDINGS= {
  '[class.mat-themed]': '_isThemed',
}

----

@Directive({
  host: {...BASE_BINDINGS, '(click)': '...'}
})
export class Dir1 {}

@Directive({
  host: {...BASE_BINDINGS, '(click)': '...'}
})
export class Dir2 {}
```

Previously when these components were shipped as part of the
library to NPM, consumers were able to consume `Dir1` and `Dir2`.
No errors showed up.

Now with Ivy, when ngcc tries to process the library, an error
will be thrown. The error is stating that the host bindings should
be an object (which they obviously are). This happens because
TypeScript transforms the object spread to individual
`Object.assign` calls (for compatibility).

The partial evaluator used by the `@Directive` annotation handler
is unable to process this expression because there is no
integrated support for `Object.assign`. In View Engine, this was
not a problem because the `metadata.json` files from the library
were used to compute the host bindings.

Fixes #34659

PR Close #34661
2020-01-23 10:29:57 -08:00
Greg Magolan
aee67f08d9 test: handle bootstrap templated_args in jasmine_node_test defaults.bzl (#34736)
PR Close #34736
2020-01-15 14:58:07 -05:00
Greg Magolan
dcff76e8b9 refactor: handle breaking changes in rules_nodejs 1.0.0 (#34736)
The major one that affects the angular repo is the removal of the bootstrap attribute in nodejs_binary, nodejs_test and jasmine_node_test in favor of using templated_args --node_options=--require=/path/to/script. The side-effect of this is that the bootstrap script does not get the require.resolve patches with explicitly loading the targets _loader.js file.

PR Close #34736
2020-01-15 14:58:07 -05:00
atscott
538d0446b5 Revert "refactor: handle breaking changes in rules_nodejs 1.0.0 (#34589)" (#34730)
This reverts commit 9bb349e1c8089ee29b82c7234a11ad4256f1d06f.

PR Close #34730
2020-01-10 14:12:15 -08:00
atscott
5e60215470 Revert "test: handle bootstrap templated_args in jasmine_node_test defaults.bzl (#34589)" (#34730)
This reverts commit da4782e67f662d37dccb89f9c642897c1266f4ce.

PR Close #34730
2020-01-10 14:12:15 -08:00
Greg Magolan
da4782e67f test: handle bootstrap templated_args in jasmine_node_test defaults.bzl (#34589)
PR Close #34589
2020-01-10 08:31:59 -08:00
Greg Magolan
9bb349e1c8 refactor: handle breaking changes in rules_nodejs 1.0.0 (#34589)
The major one that affects the angular repo is the removal of the bootstrap attribute in nodejs_binary, nodejs_test and jasmine_node_test in favor of using templated_args --node_options=--require=/path/to/script. The side-effect of this is that the bootstrap script does not get the require.resolve patches with explicitly loading the targets _loader.js file.

PR Close #34589
2020-01-10 08:31:59 -08:00
Alex Rickabaugh
74edde0a94 perf(ivy): reuse prior analysis work during incremental builds (#34288)
Previously, the compiler performed an incremental build by analyzing and
resolving all classes in the program (even unchanged ones) and then using
the dependency graph information to determine which .js files were stale and
needed to be re-emitted. This algorithm produced "correct" rebuilds, but the
cost of re-analyzing the entire program turned out to be higher than
anticipated, especially for component-heavy compilations.

To achieve performant rebuilds, it is necessary to reuse previous analysis
results if possible. Doing this safely requires knowing when prior work is
viable and when it is stale and needs to be re-done.

The new algorithm implemented by this commit is such:

1) Each incremental build starts with knowledge of the last known good
   dependency graph and analysis results from the last successful build,
   plus of course information about the set of files changed.

2) The previous dependency graph's information is used to determine the
   set of source files which have "logically" changed. A source file is
   considered logically changed if it or any of its dependencies have
   physically changed (on disk) since the last successful compilation. Any
   logically unchanged dependencies have their dependency information copied
   over to the new dependency graph.

3) During the `TraitCompiler`'s loop to consider all source files in the
   program, if a source file is logically unchanged then its previous
   analyses are "adopted" (and their 'register' steps are run). If the file
   is logically changed, then it is re-analyzed as usual.

4) Then, incremental build proceeds as before, with the new dependency graph
   being used to determine the set of files which require re-emitting.

This analysis reuse avoids template parsing operations in many circumstances
and significantly reduces the time it takes ngtsc to rebuild a large
application.

Future work will increase performance even more, by tackling a variety of
other opportunities to reuse or avoid work.

PR Close #34288
2019-12-12 13:11:45 -08:00
JoostK
b07b6f1d40 fix(ivy): avoid infinite recursion when evaluation source files (#33772)
When ngtsc comes across a source file during partial evaluation, it
would determine all exported symbols from that module and evaluate their
values greedily. This greedy evaluation strategy introduces unnecessary
work and can fall into infinite recursion when the evaluation result of
an exported expression would circularly depend on the source file. This
would primarily occur in CommonJS code, where the `exports` variable can
be used to refer to an exported variable. This variable would be
resolved to the source file itself, thereby greedily evaluating all
exported symbols and thus ending up evaluating the `exports` variable
again. This variable would be resolved to the source file itself,
thereby greedily evaluating all exported symbols and thus ending u
evaluating the `exports` variable again. This variable would be
resolved to the source file itself, thereby greedily evaluating all
exported symbols and thus ending up evaluating the `exports` variable
again. This variable would be resolved to the source file itself,
thereby greedily evaluating all exported symbols and thus ending up
evaluating the `exports` variable again. This went on for some time
until all stack frames were exhausted.

This commit introduces a `ResolvedModule` that delays the evaluation of
its exports until they are actually requested. This avoids the circular
dependency when evaluating `exports`, thereby fixing the issue.

Fix #33734

PR Close #33772
2019-11-20 14:51:37 -08:00
Alan Agius
d749dd3ea1 fix(ngcc): handle new __spreadArrays tslib helper (#33617)
We already have special cases for the `__spread` helper function and with this change we handle the new tslib helper introduced in version 1.10 `__spreadArrays`.

For more context see: https://github.com/microsoft/tslib/releases/tag/1.10.0

Fixes: #33614

PR Close #33617
2019-11-06 19:43:07 +00:00
JoostK
ce30888a26 feat(ivy): graceful evaluation of unknown or invalid expressions (#33453)
During static evaluation of expressions within ngtsc, it may occur that
certain expressions or just parts thereof cannot be statically
interpreted for some reason. The static interpreter keeps track of the
failure reason and the code path that was evaluated by means of
`DynamicValue`, which will allow descriptive errors. In some situations
however, the static interpreter would throw an exception instead,
resulting in a crash of the compilation. Not only does this cause
non-descriptive errors, more importantly does it prevent the evaluated
result from being partial, i.e. parts of the result can be dynamic if
their value does not have to be statically available to the compiler.

This commit refactors the static interpreter to never throw errors for
certain expressions that it cannot evaluate.

Resolves FW-1582

PR Close #33453
2019-11-01 00:04:02 +00:00
JoostK
a5f9a86520 feat(ivy): support undefined and null in static interpreter (#31150)
Previously, the usage of `null` and `undefined` keywords in code that is
statically interpreted by ngtsc resulted in a `DynamicValue`, as they were
not recognized as special entities. This commit adds support to interpret
these keywords.

PR Close #31150
2019-07-18 10:30:51 -07:00
Pete Bacon Darwin
7186f9c016 refactor(ivy): implement a virtual file-system layer in ngtsc + ngcc (#30921)
To improve cross platform support, all file access (and path manipulation)
is now done through a well known interface (`FileSystem`).

For testing a number of `MockFileSystem` implementations are provided.
These provide an in-memory file-system which emulates operating systems
like OS/X, Unix and Windows.

The current file system is always available via the static method,
`FileSystem.getFileSystem()`. This is also used by a number of static
methods on `AbsoluteFsPath` and `PathSegment`, to avoid having to pass
`FileSystem` objects around all the time. The result of this is that one
must be careful to ensure that the file-system has been initialized before
using any of these static methods. To prevent this happening accidentally
the current file system always starts out as an instance of `InvalidFileSystem`,
which will throw an error if any of its methods are called.

You can set the current file-system by calling `FileSystem.setFileSystem()`.
During testing you can call the helper function `initMockFileSystem(os)`
which takes a string name of the OS to emulate, and will also monkey-patch
aspects of the TypeScript library to ensure that TS is also using the
current file-system.

Finally there is the `NgtscCompilerHost` to be used for any TypeScript
compilation, which uses a given file-system.

All tests that interact with the file-system should be tested against each
of the mock file-systems. A series of helpers have been provided to support
such tests:

* `runInEachFileSystem()` - wrap your tests in this helper to run all the
wrapped tests in each of the mock file-systems.
* `addTestFilesToFileSystem()` - use this to add files and their contents
to the mock file system for testing.
* `loadTestFilesFromDisk()` - use this to load a mirror image of files on
disk into the in-memory mock file-system.
* `loadFakeCore()` - use this to load a fake version of `@angular/core`
into the mock file-system.

All ngcc and ngtsc source and tests now use this virtual file-system setup.

PR Close #30921
2019-06-25 16:25:24 -07:00
JoostK
3fb73ac62b fix(ivy): support equality operators in static interpreter (#31145)
Previously, the usage of equality operators ==, ===, != and !== was not
supported in ngtsc's static interpreter. This commit adds support for
such operators and includes tests.

Fixes #31076

PR Close #31145
2019-06-24 18:47:02 -07:00
Matt Lewis
f0395836b6 fix(ivy): evaluate non existing property access as undefined (#30738)
Closes #30726

PR Close #30738
2019-06-19 15:44:05 -07:00
JoostK
9d9c9e43e5 feat(ivy): static evaluation of TypeScript's __spread helper (#30492)
The usage of array spread syntax in source code may be downleveled to a
call to TypeScript's `__spread` helper function from `tslib`, depending
on the options `downlevelIteration` and `emitHelpers`. This proves
problematic for ngcc when it is processing ES5 formats, as the static
evaluator won't be able to interpret those calls.

A custom foreign function resolver is not sufficient in this case, as
`tslib` may be emitted into the library code itself. In that case, a
helper function can be resolved to an actual function with body, such
that it won't be considered as foreign function. Instead, a reflection
host can now indicate that the definition of a function corresponds with
a certain TypeScript helper, such that it becomes statically evaluable
in ngtsc.

Resolves #30299

PR Close #30492
2019-06-10 23:53:04 +00:00
JoostK
1b613c3ebf fix(ivy): evaluate external declaration usages as dynamic (#30247)
Previously, ngtsc would fail to evaluate expressions that access properties
from e.g. the `window` object. This resulted in hard to debug error messages
as no indication on where the problem originated was present in the output.

This commit cleans up the handling of unknown property accesses, such that
evaluating such expressions no longer fail but instead result in a `DynamicValue`.

Fixes #30226

PR Close #30247
2019-05-16 11:46:00 -07:00
Pete Bacon Darwin
0a0b4c1d8f feat(ivy): track file dependencies due to partial evaluation (#30238)
As part of incremental compilation performance improvements, we need
to track the dependencies of files due to expressions being evaluated by
the `PartialEvaluator`.

The `PartialEvaluator` now accepts a `DependencyTracker` object, which is
used to track which files are visited when evaluating an expression.
The interpreter computes this `originatingFile` and stores it in the evaluation
`Context` so it can pass this to the `DependencyTracker.

The `IncrementalState` object implements this interface, which allows it to be
passed to the `PartialEvaluator` and so capture the file dependencies.

PR Close #30238
2019-05-10 12:10:40 -07:00
Kristiyan Kostadinov
ae93ba1140 fix(ivy): don't throw error when evaluating function with more than one statement (#30061)
Resolves functions with more than one statement to unknown dynamic values, rather than throwing an error.

PR Close #30061
2019-04-24 11:32:56 -07:00
JoostK
c3c0df9d56 fix(ivy): let ngtsc evaluate default parameters in the callee context (#29888)
Previously, during the evaluation of a function call where no argument
was provided for a parameter that has a default value, the default value
would be taken from the context of the caller, instead of the callee.

This commit fixes the behavior by resolving the default value of a
parameter in the context of the callee.

PR Close #29888
2019-04-19 19:30:40 -07:00
JoostK
cb34514d05 feat(ivy): let ngtsc evaluate the spread operator in function calls (#29888)
Previously, ngtsc's static evaluator did not take spread operators into
account when evaluating function calls, nor did it handle rest arguments
correctly. This commit adds support for static evaluation of these
language features.

PR Close #29888
2019-04-19 19:30:40 -07:00
JoostK
725148a44d feat(ivy): let ngtsc statically evaluate Array.concat calls (#29887)
Previously, only static evaluation of `Array.slice` was implemented in
ngtsc's static evaluator. This commit adds support for `Array.concat`.

Closes #29835

PR Close #29887
2019-04-17 12:49:13 -07:00
Pete Bacon Darwin
06859f1335 refactor(compiler-cli): track visited source files in PartialEvaluator (#29539)
PR Close #29539
2019-04-01 11:53:08 -07:00
Alex Rickabaugh
ae4a86e3b5 fix(ivy): don't track identifiers of ffr-resolved references (#29387)
This fix is for a bug in the ngtsc PartialEvaluator, which statically
evaluates expressions.

Sometimes, evaluating a reference requires resolving a function which is
declared in another module, and thus no function body is available. To
support this case, the PartialEvaluator has the concept of a foreign
function resolver.

This allows the interpretation of expressions like:

const router = RouterModule.forRoot([]);

even though the definition of the 'forRoot' function has no body. In
ngtsc today, this will be resolved to a Reference to RouterModule itself,
via the ModuleWithProviders foreign function resolver.

However, the PartialEvaluator also associates any Identifiers in the path
of this resolution with the Reference. This is done so that if the user
writes

const x = imported.y;

'x' can be generated as a local identifier instead of adding an import for
'y'.

This was at the heart of a bug. In the above case with 'router', the
PartialEvaluator added the identifier 'router' to the Reference generated
(through FFR) to RouterModule.

This is not correct. References that result from FFR expressions may not
have the same value at runtime as they do at compile time (indeed, this is
not the case for ModuleWithProviders). The Reference generated via FFR is
"synthetic" in the sense that it's constructed based on a useful
interpretation of the code, not an accurate representation of the runtime
value. Therefore, it may not be legal to refer to the Reference via the
'router' identifier.

This commit adds the ability to mark such a Reference as 'synthetic', which
allows the PartialEvaluator to not add the 'router' identifier down the
line. Tests are included for both the PartialEvaluator itself as well as the
resultant buggy behavior in ngtsc overall.

PR Close #29387
2019-03-19 01:10:17 -04:00
Alex Rickabaugh
a06824aef6 fix(ivy): correctly evaluate enum references in template expressions (#29062)
The ngtsc partial evaluator previously would not handle an enum reference
inside a template string expression correctly. Enums are resolved to an
`EnumValue` type, which has a `resolved` property with the actual value.

When effectively toString-ing a `ResolvedValue` as part of visiting a
template expression, the partial evaluator needs to translate `EnumValue`s
to their fully resolved value, which this commit does.

PR Close #29062
2019-03-01 15:47:24 -08:00
Alex Rickabaugh
a23a0bc3a4 feat(ivy): support tracking the provenance of DynamicValue (#29033)
DynamicValues are generated whenever a partially evaluated expression is
unable to be resolved statically. They contain a reference to the ts.Node
which wasn't resolvable.

They can also be nested. For example, the expression 'a + b' is resolvable
only if 'a' and 'b' are themselves resolvable. If either 'a' or 'b' resolve
to a DynamicValue, the whole expression must also resolve to a DynamicValue.

Previously, if 'a' resolved to a DynamicValue, the entire expression might
have been resolved to the same DynamicValue. This correctly indicated that
the expression wasn't resolvable, but didn't return a reference to the
shallow node that couldn't be resolved (the expression 'a + b'), only a
reference to the deep node that couldn't be resolved ('a').

In certain situations, it's very useful to know the shallow unresolvable
node (for example, to use it verbatim in the output). To support this,
the partial evaluator is updated to always wrap DynamicValue to point to
each unresolvable expression as it's processed, ensuring the receiver can
determine exactly which expression node failed to resolve.

PR Close #29033
2019-03-01 15:18:13 -08:00
Greg Magolan
ea09430039 build: rules_nodejs 0.26.0 & use @npm instead of @ngdeps now that downstream angular build uses angular bundles (#28871)
PR Close #28871
2019-02-28 12:06:36 -08:00
Alex Rickabaugh
d127d05dc3 fix(ivy): correctly resolve shorthand property declarations (#28936)
The partial evaluator in ngtsc can handle a shorthand property declaration
in the middle evaluation, but fails if evaluation starts at the shorthand
property itself. This is because evaluation starts at the ts.Identifier
of the property (the ts.Expression representing it), not the ts.Declaration
for the property.

The fix for this is to detect in TypeScriptReflectionHost when a ts.Symbol
refers to a shorthand property, and to use the ts.TypeChecker method
getShorthandAssignmentValueSymbol() to resolve the value of the assignment
instead.

FW-1089 #resolve

PR Close #28936
2019-02-27 08:48:54 -08:00
Wassim Chegham
ce68b4d839 style: enforce buildifier lint on CI (#28186)
PR Close #28186
2019-02-26 16:57:41 -08:00
Alex Rickabaugh
423b39e216 feat(ivy): use fileNameToModuleName to emit imports when it's available (#28523)
The ultimate goal of this commit is to make use of fileNameToModuleName to
get the module specifier to use when generating an import, when that API is
available in the CompilerHost that ngtsc is created with.

As part of getting there, the way in which ngtsc tracks references and
generates import module specifiers is refactored considerably. References
are tracked with the Reference class, and previously ngtsc had several
different kinds of Reference. An AbsoluteReference represented a declaration
which needed to be imported via an absolute module specifier tracked in the
AbsoluteReference, and a RelativeReference represented a declaration from
the local program, imported via relative path or referred to directly by
identifier if possible. Thus, how to refer to a particular declaration was
encoded into the Reference type _at the time of creation of the Reference_.

This commit refactors that logic and reduces Reference to a single class
with no subclasses. A Reference represents a node being referenced, plus
context about how the node was located. This context includes a
"bestGuessOwningModule", the compiler's best guess at which absolute
module specifier has defined this reference. For example, if the compiler
arrives at the declaration of CommonModule via an import to @angular/common,
then any references obtained from CommonModule (e.g. NgIf) will also be
considered to be owned by @angular/common.

A ReferenceEmitter class and accompanying ReferenceEmitStrategy interface
are introduced. To produce an Expression referring to a given Reference'd
node, the ReferenceEmitter consults a sequence of ReferenceEmitStrategy
implementations.

Several different strategies are defined:

- LocalIdentifierStrategy: use local ts.Identifiers if available.
- AbsoluteModuleStrategy: if the Reference has a bestGuessOwningModule,
  import the node via an absolute import from that module specifier.
- LogicalProjectStrategy: if the Reference is in the logical project
  (is under the project rootDirs), import the node via a relative import.
- FileToModuleStrategy: use a FileToModuleHost to generate the module
  specifier by which to import the node.

Depending on the availability of fileNameToModuleName in the CompilerHost,
then, a different collection of these strategies is used for compilation.

PR Close #28523
2019-02-13 19:13:11 -08:00
Alex Rickabaugh
1c39ad38d3 feat(ivy): reference external classes by their exported name (#27743)
Previously, ngtsc would assume that a given directive/pipe being imported
from an external package was importable using the same name by which it
was declared. This isn't always true; sometimes a package will export a
directive under a different name. For example, Angular frequently prefixes
directive names with the 'ɵ' character to indicate that they're part of
the package's private API, and not for public consumption.

This commit introduces the TsReferenceResolver class which, given a
declaration to import and a module name to import it from, can determine
the exported name of the declared class within the module. This allows
ngtsc to pick the correct name by which to import the class instead of
making assumptions about how it was exported.

This resolver is used to select a correct symbol name when creating an
AbsoluteReference.

FW-517 #resolve
FW-536 #resolve

PR Close #27743
2019-01-08 16:36:18 -08:00
Alex Rickabaugh
f4a9f5dae8 refactor(ivy): prep ngtsc and ngcc for upcoming import resolution work (#27743)
Upcoming work to implement import resolution will change the dependencies
of some higher-level classes in ngtsc & ngcc. This necessitates changes in
how these classes are created and the lifecycle of the ts.Program in ngtsc
& ngcc.

To avoid complicating the implementation work with refactoring as a result
of the new dependencies, the refactoring is performed in this commit as a
separate prepatory step.

In ngtsc, the testing harness is modified to allow easier access to some
aspects of the ts.Program.

In ngcc, the main change is that the DecorationAnalyzer is created with the
ts.Program as a constructor parameter. This is not a lifecycle change, as
it was previously created with the ts.TypeChecker which is derived from the
ts.Program anyways. This change requires some reorganization in ngcc to
accommodate, especially in testing harnesses where DecorationAnalyzer is
created manually in a number of specs.

PR Close #27743
2019-01-08 16:36:18 -08:00
Alex Rickabaugh
2a6108af97 refactor(ivy): split apart the 'metadata' package in the ngtsc compiler (#27743)
This refactoring moves code around between a few of the ngtsc subpackages,
with the goal of having a more logical package structure. Additional
interfaces are also introduced where they make sense.

The 'metadata' package formerly contained both the partial evaluator,
the TypeScriptReflectionHost as well as some other reflection functions,
and the Reference interface and various implementations. This package
was split into 3 parts.

The partial evaluator now has its own package 'partial_evaluator', and
exists behind an interface PartialEvaluator instead of a top-level
function. In the future this will be useful for reducing churn as the
partial evaluator becomes more complicated.

The TypeScriptReflectionHost and other miscellaneous functions have moved
into a new 'reflection' package. The former 'host' package which contained
the ReflectionHost interface and associated types was also merged into this
new 'reflection' package.

Finally, the Reference APIs were moved to the 'imports' package, which will
consolidate all import-related logic in ngtsc.

PR Close #27743
2019-01-08 16:36:18 -08:00