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Refactor coffeescript export support: move CS-specific parsing

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into CS package.
This commit is contained in:
David Glasser
2013-06-20 10:52:34 -07:00
parent 40078b8bee
commit 974bc116be
3 changed files with 88 additions and 84 deletions
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87
packages/coffeescript/plugin/compile-coffeescript.js
View File

@@ -1,6 +1,74 @@
var fs = Npm.require('fs');
var path = Npm.require('path');
var coffee = Npm.require('coffee-script');
var _ = Npm.require('underscore');
var stripExportedVars = function (source, exports) {
if (!exports || _.isEmpty(exports))
return source;
var lines = source.split("\n");
// We make the following assumptions, based on the output of CoffeeScript
// 1.6.3.
// - The var declaration in question is not indented and is the first such
// var declaration. (CoffeeScript only produces one var line at each
// scope and there's only one top-level scope.) All relevant variables
// are actually on this line.
// - The user hasn't used a ###-comment containing a line that looks like
// a var line, to produce something like
// /* bla
// var foo;
// */
// before an actual var line. (ie, we do NOT attempt to figure out if
// we're inside a /**/ comment, which is produced by ### comments.)
// - The var in question is not assigned to in the declaration, nor are any
// other vars on this line. (CoffeeScript does produce some assignments
// but only for internal helpers generated by CoffeeScript, and they end
// up on subsequent lines.)
// XXX relax these assumptions by doing actual JS parsing (eg with jsparse).
// I'd do this now, but there's no easy way to "unparse" a jsparse AST.
var foundVarLine = false;
lines = _.map(lines, function (line) {
if (foundVarLine)
return line;
var match = /^var (.+)([,;])$/.exec(line);
if (!match)
return line;
foundVarLine = true;
// If there's an assignment on this line, we assume that there are ONLY
// assignments and that the var we are looking for is not declared. (Part
// of our strong assumption about the layout of this code.)
if (match[1].indexOf('=') !== -1)
return line;
var vars = match[1].split(', ');
vars = _.difference(vars, exports);
if (!_.isEmpty(vars))
return "var " + vars.join(', ') + match[2];
// We got rid of all the vars on this line. Drop the whole line if this
// didn't continue to the next line, otherwise keep just the 'var '.
return match[2] === ';' ? '' : 'var';
});
return lines.join('\n');
};
var addSharedHeader = function (source) {
// We want the symbol "share" to be visible to all CoffeeScript files in the
// package (and shared between them), but not visible to JavaScript
// files. (That's because we don't want to introduce two competing ways to
// make package-local variables into JS ("share" vs assigning to non-var
// variables).) The following hack accomplishes that: "__coffeescriptShare"
// will be visible at the package level and "share" at the file level. This
// should work both in "package" mode where __coffeescriptShare will be added
// as a var in the package closure, and in "app" mode where it will end up as
// a global.
return ("__coffeescriptShare = typeof __coffeescriptShare === 'object' ? " +
"__coffeescriptShare : {}; " +
"var share = __coffeescriptShare;" +
source);
};
var handler = function (compileStep) {
var source = compileStep.read().toString('utf8');
@@ -21,27 +89,14 @@ var handler = function (compileStep) {
);
}
// We want the symbol "share" to be visible to all CoffeeScript files in the
// package (and shared between them), but not visible to JavaScript
// files. (That's because we don't want to introduce two competing ways to
// make package-local variables into JS ("share" vs assigning to non-var
// variables).) The following hack accomplishes that: "__coffeescriptShare"
// will be visible at the package level and "share" at the file level. This
// should work both in "package" mode where __coffeescriptShare will be added
// as a var in the package closure, and in "app" mode where it will end up as
// a global.
//
// We need a newline after this (which may require a source map to be
// adjusted), to not conflict with stripVarFromExports.
output = ("__coffeescriptShare = typeof __coffeescriptShare === 'object' ? __coffeescriptShare : {}; " +
"var share = __coffeescriptShare;\n" + output);
compileStep.addJavaScript({
path: compileStep.inputPath + ".js",
sourcePath: compileStep.inputPath,
data: output,
lineForLine: false,
stripVarFromExports: true
linkerUnitTransform: function (source, exports) {
return addSharedHeader(stripExportedVars(source, exports));
}
});
};

83
tools/linker.js
View File

@@ -54,10 +54,10 @@ _.extend(Module.prototype, {
// source: the source code
// servePath: the path where it would prefer to be served if possible
addFile: function (source, servePath, sourcePath, includePositionInErrors,
stripVarFromExports) {
linkerUnitTransform) {
var self = this;
self.files.push(new File(source, servePath, sourcePath,
includePositionInErrors, stripVarFromExports));
includePositionInErrors, linkerUnitTransform));
},
@@ -257,7 +257,7 @@ var writeSymbolTree = function (symbolTree, indent) {
///////////////////////////////////////////////////////////////////////////////
var File = function (source, servePath, sourcePath, includePositionInErrors,
stripVarFromExports) {
linkerUnitTransform) {
var self = this;
// source code for this file (a string)
@@ -276,9 +276,11 @@ var File = function (source, servePath, sourcePath, includePositionInErrors,
// the source of each unit, in order, will give self.source.
self.units = [];
// Should we try to ensure that exports are not also declared as top-level
// vars? (eg, for CoffeeScript.)
self.stripVarFromExports = stripVarFromExports;
// A function which transforms the source code once all exports are
// known. (eg, for CoffeeScript.)
self.linkerUnitTransform = linkerUnitTransform || function (source, exports) {
return source;
};
self._unitize();
};
@@ -302,7 +304,7 @@ _.extend(File.prototype, {
// numbers don't change between input and output. In this case,
// sourceWidth is ignored.
// - sourceWidth: width in columns to use for the source code
// - exports: the exports to remove, if stripVarFromExports was set
// - exports: the module's exports
getLinkedOutput: function (options) {
var self = this;
@@ -312,7 +314,7 @@ _.extend(File.prototype, {
if (options.preserveLineNumbers) {
// Ugly version
return "(function(){" +
self._maybeStripVars(self.source, options.exports) + "\n})();\n";
self.linkerUnitTransform(self.source, options.exports) + "\n})();\n";
}
// Pretty version
@@ -340,7 +342,7 @@ _.extend(File.prototype, {
// already inside a comment.
var num = 1;
_.each(self.units, function (unit) {
var unitSource = self._maybeStripVars(unit.source, options.exports);
var unitSource = self.linkerUnitTransform(unit.source, options.exports);
var lines = unitSource.split('\n');
_.each(lines, function (line) {
@@ -432,59 +434,6 @@ _.extend(File.prototype, {
buf += line;
});
unit.source = buf;
},
_maybeStripVars: function (source, exports) {
var self = this;
if (!self.stripVarFromExports || !exports || _.isEmpty(exports))
return source;
var lines = source.split("\n");
// We make the following assumptions, based on the output of CoffeeScript
// 1.6.3.
// - The var declaration in question is not indented and is the first such
// var declaration. (CoffeeScript only produces one var line at each
// scope and there's only one top-level scope.) All relevant variables
// are actually on this line.
// - The user hasn't used a ###-comment containing a line that looks like
// a var line, to produce something like
// /* bla
// var foo;
// */
// before an actual var line. (ie, we do NOT attempt to figure out if
// we're inside a /**/ comment, which is produced by ### comments.)
// - The var in question is not assigned to in the declaration, nor are
// any other vars on this line. (CoffeeScript does produce some
// assignments but only for internal helpers generated by CoffeeScript,
// and they end up on subsequent lines.)
// XXX relax these assumptions by doing actual JS parsing (eg with jsparse).
// I'd do this now, but there's no easy way to "unparse" a jsparse AST.
var foundVarLine = false;
lines = _.map(lines, function (line) {
if (foundVarLine)
return line;
var match = /^var (.+)([,;])$/.exec(line);
if (!match)
return line;
foundVarLine = true;
// If there's an assignment on this line, we assume that there are ONLY
// assignments and that the var we are looking for is not declared. (Part
// of our strong assumption about the layout of this code.)
if (match[1].indexOf('=') !== -1)
return line;
var vars = match[1].split(', ');
vars = _.difference(vars, exports);
if (!_.isEmpty(vars))
return "var " + vars.join(', ') + match[2];
// We got rid of all the vars on this line. Drop the whole line if this
// didn't continue to the next line, otherwise keep just the 'var '.
return match[2] === ';' ? '' : 'var';
});
return lines.join('\n');
}
});
@@ -612,10 +561,10 @@ _.extend(Unit.prototype, {
// - includePositionInErrors: true to include line and column
// information in errors. set to false if, eg, this is the output
// of coffeescript. (XXX replace with real sourcemaps)
// - stripVarFromExports: true if we should look at the top of the file
// for a "var" declaration which may declare some exports as unassigned
// vars, and if so, remove the var declaration. (This is designed
// to work with the output of the CoffeeScript compiler.)
// - linkerUnitTransform: if given, this function will be called
// when the module is being linked with the source of the unit
// and an array of the exports of the module; the unit's source will
// be replaced by what the function returns.
//
// forceExport: an array of symbols (as dotted strings) to force the
// module to export, even if it wouldn't otherwise
@@ -648,7 +597,7 @@ var prelink = function (options) {
_.each(options.inputFiles, function (f) {
module.addFile(f.source, f.servePath, f.sourcePath,
f.includePositionInErrors,
f.stripVarFromExports);
f.linkerUnitTransform);
});
var files = module.getLinkedFiles();

2
tools/packages.js
View File

@@ -372,7 +372,7 @@ _.extend(Slice.prototype, {
sourcePath: options.sourcePath,
servePath: path.join(self.pkg.serveRoot, options.path),
includePositionInErrors: options.lineForLine,
stripVarFromExports: !!options.stripVarFromExports
linkerUnitTransform: options.linkerUnitTransform
});
},
addAsset: function (options) {