github.com/joomcode/cue@v0.4.4-0.20221111115225-539fe3512047/cue/parser/interface.go (about)

     1  // Copyright 2018 The CUE Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // This file contains the exported entry points for invoking the
    16  
    17  package parser
    18  
    19  import (
    20  	"github.com/joomcode/cue/cue/ast"
    21  	"github.com/joomcode/cue/cue/ast/astutil"
    22  	"github.com/joomcode/cue/cue/errors"
    23  	"github.com/joomcode/cue/cue/token"
    24  	"github.com/joomcode/cue/internal/source"
    25  )
    26  
    27  // Option specifies a parse option.
    28  type Option func(p *parser)
    29  
    30  var (
    31  	// PackageClauseOnly causes parsing to stop after the package clause.
    32  	PackageClauseOnly Option = packageClauseOnly
    33  	packageClauseOnly        = func(p *parser) {
    34  		p.mode |= packageClauseOnlyMode
    35  	}
    36  
    37  	// ImportsOnly causes parsing to stop parsing after the import declarations.
    38  	ImportsOnly Option = importsOnly
    39  	importsOnly        = func(p *parser) {
    40  		p.mode |= importsOnlyMode
    41  	}
    42  
    43  	// ParseComments causes comments to be parsed.
    44  	ParseComments Option = parseComments
    45  	parseComments        = func(p *parser) {
    46  		p.mode |= parseCommentsMode
    47  	}
    48  
    49  	// Trace causes parsing to print a trace of parsed productions.
    50  	Trace    Option = traceOpt
    51  	traceOpt        = func(p *parser) {
    52  		p.mode |= traceMode
    53  	}
    54  
    55  	// DeclarationErrors causes parsing to report declaration errors.
    56  	DeclarationErrors Option = declarationErrors
    57  	declarationErrors        = func(p *parser) {
    58  		p.mode |= declarationErrorsMode
    59  	}
    60  
    61  	// AllErrors causes all errors to be reported (not just the first 10 on different lines).
    62  	AllErrors Option = allErrors
    63  	allErrors        = func(p *parser) {
    64  		p.mode |= allErrorsMode
    65  	}
    66  
    67  	// AllowPartial allows the parser to be used on a prefix buffer.
    68  	AllowPartial Option = allowPartial
    69  	allowPartial        = func(p *parser) {
    70  		p.mode |= partialMode
    71  	}
    72  )
    73  
    74  // FromVersion specifies until which legacy version the parser should provide
    75  // backwards compatibility.
    76  func FromVersion(version int) Option {
    77  	if version >= 0 {
    78  		version++
    79  	}
    80  	// Versions:
    81  	// <0:  major version 0 (counting -1000 + x, where x = 100*m+p in 0.m.p
    82  	// >=0: x+1 in 1.x.y
    83  	return func(p *parser) { p.version = version }
    84  }
    85  
    86  func version0(minor, patch int) int {
    87  	return -1000 + 100*minor + patch
    88  }
    89  
    90  // DeprecationError is a sentinel error to indicate that an error is
    91  // related to an unsupported old CUE syntax.
    92  type DeprecationError struct {
    93  	Version int
    94  }
    95  
    96  func (e *DeprecationError) Error() string {
    97  	return "try running `cue fix` (possibly with an earlier version, like v0.2.2) to upgrade"
    98  }
    99  
   100  // Latest specifies the latest version of the parser, effectively setting
   101  // the strictest implementation.
   102  const Latest = latest
   103  
   104  const latest = -600
   105  
   106  // FileOffset specifies the File position info to use.
   107  func FileOffset(pos int) Option {
   108  	return func(p *parser) { p.offset = pos }
   109  }
   110  
   111  // A mode value is a set of flags (or 0).
   112  // They control the amount of source code parsed and other optional
   113  // parser functionality.
   114  type mode uint
   115  
   116  const (
   117  	packageClauseOnlyMode mode = 1 << iota // stop parsing after package clause
   118  	importsOnlyMode                        // stop parsing after import declarations
   119  	parseCommentsMode                      // parse comments and add them to AST
   120  	partialMode
   121  	traceMode             // print a trace of parsed productions
   122  	declarationErrorsMode // report declaration errors
   123  	allErrorsMode         // report all errors (not just the first 10 on different lines)
   124  )
   125  
   126  // ParseFile parses the source code of a single CUE source file and returns
   127  // the corresponding File node. The source code may be provided via
   128  // the filename of the source file, or via the src parameter.
   129  //
   130  // If src != nil, ParseFile parses the source from src and the filename is
   131  // only used when recording position information. The type of the argument
   132  // for the src parameter must be string, []byte, or io.Reader.
   133  // If src == nil, ParseFile parses the file specified by filename.
   134  //
   135  // The mode parameter controls the amount of source text parsed and other
   136  // optional parser functionality. Position information is recorded in the
   137  // file set fset, which must not be nil.
   138  //
   139  // If the source couldn't be read, the returned AST is nil and the error
   140  // indicates the specific failure. If the source was read but syntax
   141  // errors were found, the result is a partial AST (with Bad* nodes
   142  // representing the fragments of erroneous source code). Multiple errors
   143  // are returned via a ErrorList which is sorted by file position.
   144  func ParseFile(filename string, src interface{}, mode ...Option) (f *ast.File, err error) {
   145  
   146  	// get source
   147  	text, err := source.Read(filename, src)
   148  	if err != nil {
   149  		return nil, err
   150  	}
   151  
   152  	var pp parser
   153  	defer func() {
   154  		if pp.panicking {
   155  			_ = recover()
   156  		}
   157  
   158  		// set result values
   159  		if f == nil {
   160  			// source is not a valid Go source file - satisfy
   161  			// ParseFile API and return a valid (but) empty
   162  			// *File
   163  			f = &ast.File{
   164  				// Scope: NewScope(nil),
   165  			}
   166  		}
   167  
   168  		err = errors.Sanitize(pp.errors)
   169  	}()
   170  
   171  	// parse source
   172  	pp.init(filename, text, mode)
   173  	f = pp.parseFile()
   174  	if f == nil {
   175  		return nil, pp.errors
   176  	}
   177  	f.Filename = filename
   178  	astutil.Resolve(f, pp.errf)
   179  
   180  	return f, pp.errors
   181  }
   182  
   183  // ParseExpr is a convenience function for parsing an expression.
   184  // The arguments have the same meaning as for Parse, but the source must
   185  // be a valid CUE (type or value) expression. Specifically, fset must not
   186  // be nil.
   187  func ParseExpr(filename string, src interface{}, mode ...Option) (ast.Expr, error) {
   188  	// get source
   189  	text, err := source.Read(filename, src)
   190  	if err != nil {
   191  		return nil, err
   192  	}
   193  
   194  	var p parser
   195  	defer func() {
   196  		if p.panicking {
   197  			_ = recover()
   198  		}
   199  		err = errors.Sanitize(p.errors)
   200  	}()
   201  
   202  	// parse expr
   203  	p.init(filename, text, mode)
   204  	// Set up pkg-level scopes to avoid nil-pointer errors.
   205  	// This is not needed for a correct expression x as the
   206  	// parser will be ok with a nil topScope, but be cautious
   207  	// in case of an erroneous x.
   208  	e := p.parseRHS()
   209  
   210  	// If a comma was inserted, consume it;
   211  	// report an error if there's more tokens.
   212  	if p.tok == token.COMMA && p.lit == "\n" {
   213  		p.next()
   214  	}
   215  	if p.mode&partialMode == 0 {
   216  		p.expect(token.EOF)
   217  	}
   218  
   219  	if p.errors != nil {
   220  		return nil, p.errors
   221  	}
   222  	astutil.ResolveExpr(e, p.errf)
   223  
   224  	return e, p.errors
   225  }
   226  
   227  // parseExprString is a convenience function for obtaining the AST of an
   228  // expression x. The position information recorded in the AST is undefined. The
   229  // filename used in error messages is the empty string.
   230  func parseExprString(x string) (ast.Expr, error) {
   231  	return ParseExpr("", []byte(x))
   232  }